Tantalum amido-complexes with chelate ligands useful for CVD and ALD of TaN ...

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TANTALUM AMIDO-COMPLEXES WITH
CHELATE LIGANDS USEFUL FOR CVD AND
ALD OF TAN AND TA205 THIN FILMS

CROSS-REFERENCE TO RELATED 5
APPLICATION

The benefit of U.S. Provisional Patent Application 60/885, 459 filed Jan. 18,2007 in the names of Tianniu Chen, et al. for "TANTALUM AMIDO-COMPLEXES WITH CHELATE 10 LIGANDS USEFUL FOR CVD AND ALD OF TaN AND Ta205" is hereby claimed under the provisions of 3 5 USC 119. The disclosure of said U.S. Provisional Patent Application 60/885,459 is hereby incorporated herein by reference, in its entirety, for all purposes. 15

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to precursor compositions 20 that are useful for forming tantalum-containing films, e.g., by chemical vapor deposition (CVD) or atomic layer deposition (ALD), as well as to tantalum-containing barrier layers or films and to copper-metallized semiconductor device structures including tantalum-containing layers or films. 25

2. Description of the Related Art

In the field of semiconductor manufacturing, copper (Cu) and low k dielectrics are being increasingly employed in high performance silicon integrated circuits. Since Cu is very mobile in silicon (Si) and silicon dioxide (Si02), effective 30 diffusion barriers against Cu migration are required for the use of Cu metallization, inasmuch as the copper/interlayer dielectric interface determines the stability and reliability of the metallization scheme.

A variety of refractory metals, refractory metal nitrides, 35 and metal-silicon-nitrogen compounds have been intensively investigated foruse as barrier material. See, forexample, U.S. Pat. No. 6,951,804 to Seutter et al. and U.S. Pat. No. 6,960, 675 to Chen et al. Each of these U.S. patents is incorporated herein by reference in their entirety. 40

Among such materials, tantalum (Ta) and tantalum nitrides (TaN) are considered to be among the most promising candidates because of their stability under high temperature, high degree of adhesion, low resistivity, uniformity of their films and their inertness towards Cu. 45

As the size of the pattern shrinks and the aspect ratio increases, vapor deposition techniques, e.g., chemical vapor deposition (CVD), atomic layer deposition (ALD), digital CVD, pulsed CVD, or the like, are necessary to deposit the barrier layer, in order to minimize barrier layer thickness 50 while achieving effective barrier properties.

Against this background of continuous shrinkage in feature size and progressive increase in aspect ratio, chemical vapor deposition (CVD) and atomic layer deposition (ALD) are increasingly preferred for depositing thin, conformal and 55 smooth barrier layers in vias and trenches. For such applications, suitable tantalum precursors are required for forming tantalum-containing barrier material on substrates.

From a practical standpoint, Ta amides, such as, PDMAT [Ta(NMe2)5], andPEMAT [Ta(NEtMe)5] andTaimides, such 60 as, TBTDET [t-BuN=Ta(NEt2)3], and TAIMATA [t-AmN=Ta(NMe2)3] represent some currently available TaN precursors. Thermal stability of amides is problematic. For example, PDMAT is a solid with a melting point of 167° C. However, PDMAT decomposes at temperatures above 80° 65 C. PEMAT is a low melting point solid. PEMAT also decomposes at temperatures above 80° C.

There i s a continuing need in the art for tantalum precursors useful for deposition applications, e.g., to form copper migration barrier structures.

In current practice, copper migration barrier structures are formed by reactive sputter deposition of a TaN layer onto a patterned, nominally dense dielectric, followed by sputter deposition of Ta metal prior to sputter deposition of a copper seed layer.

There is correspondingly a need for barrier layers, e.g., for copper metallization of semiconductor device structures, that do not introduce nitrogen to the underlying dielectric film.

SUMMARY OF THE INVENTION

Aspects of various embodiments of the present invention relate generally to precursor compositions for forming tantalum-containing films, as well as to the tantalum-containing films, such as may be employed as barrier layers in semiconductor devices utilizing copper metallization, as well as to semiconductor device structures including tantalum-containing films.

In one aspect, an embodiment of the present invention relates to a tantalum compound of Formula I:

wherein: R1, R2, R3 and R4 can be the same as or different from one another, and each is independently selected from the group consisting of hydrocarbyl, alkyl, silyl, and, alkylamino.

In some embodiments, in Formula I, R1 and R2 cannot both be isopropyl at the same time and/or R1 and R2 cannot both be cyclohexyl at the same time.

One or more embodiments of the invention in another aspect relate to a tantalum precursor formulation, including a tantalum compound (Formulae I) as described above, in a solvent medium.

An example of a suitable solvent medium is an organic solvent, including but not limited to, hydrocarbon solvents such as pentane, hexane, heptane, octane, decane, THF, ether (e.g., dimethylether (DME)) and aromatic solvents such as toluene.

Other suitable solvents may be used.

In a further aspect, embodiments of the invention relate to a method of synthesizing a tantalum compound (Formula I) as described above, in which the method includes conducting synthesis according to Scheme 1 or Scheme la below:

-continued

(Scheme 1a).

NR3R4
| v„nr3r4r2

M(NR3R4)5 R'n=c=nr?,

3R4RN I

/"' NNR3R4

A still further aspect of embodiments of the invention relate to a method of forming a tantalum-containing material on a substrate, including volatilizing a tantalum compound of Formula I as described above, to form a precursor vapor, and depositing tantalum on the substrate from the precursor vapor under deposition conditions therefor.

It is to be appreciated, however, that (according to one or more embodiments of the invention) the tantalum-containing material on a substrate, the tantalum-containing barrier layer on a substrate, or devices containing same, or methods for making the same, may involve (in whole, or in part) the tantalum compounds of Formula I.

In another aspect, one or more embodiments of the present invention relate to a semiconductor device structure, including a dielectric layer, a barrier layer overlying (or, for example, directly on) the dielectric layer, and a copper metallization overlying (or, for example, directly on) the barrier layer, wherein the barrier layer is optionally amorphous. See, for example, FIG. 5 hereof.

A still further aspect of one or more embodiments of the invention relates to a method of forming a Ta-containing barrier layer on a dielectric layer which, in turn, is on a substrate. The Ta-containing barrier layer may be formed by a process including CVD or ALD using precursors of Formula I as described herein. According to one embodiment of the present invention, the CVD or ALD is conducted at a temperature below about 400° C, in a reducing atmosphere.

Yet another aspect of one or more embodiments of the invention relates to a method of inhibiting copper migration in a structure including copper and material adversely affected by copper migration (and/or improving poor adhesion between the copper layer and the barrier layer underneath), comprising interposing a Ta-containing barrier layer between said copper and such material using precursors of Formula I as described herein. According to one embodiment of the present invention, the CVD or ALD is conducted at a temperature below about 400° C, in a reducing atmosphere (e.g., a suitable nitriding atmosphere such as NH3— for example—ammonia gas or ammonia plasma).

Additional aspects of one or more embodiments of the present invention relate to making a semiconductor device, comprising forming a migration barrier by a vapor deposition process using a vapor deposition precursor including a tantalum compound (Formula I) as described herein, and semiconductor manufacturing methods including use of a tantalum compounds of such type.

The metal source precursors of the invention are volatile and thermally stable, and are usefully employed as precursors for CVD, ALD and/or digital CVD (sometimes referred to as rapid vapor deposition, or RVD) under reduced pressure deposition conditions in corresponding CVD, ALD or digital CVD reactors. In digital CDV, as in ALD, the substrate is sequentially exposed precursors in gaseous form. In digital

CDV the process is repeated until a substrate coated with multiple layers reaches a desired thickness. The resulting coated substrate has a high conformality. Digital CVD differs from ALD in that the layers in digital CVD can be deposited more quickly.

The compositions of the present invention can be delivered to the CVD, ALD or digital CVD reactors in a variety of ways. For example, a liquid delivery system may be utilized, with the solid precursor(s) being dissolved in organic solvents, and liquid delivery processes being used to meter the solution into a vaporizer for transport of the vapor to the reactor. Alternatively, a combined liquid delivery and flash vaporization process unit may be employed, to enable low volatility materials to be volumetrically delivered, so that reproducible transport and deposition are achieved without thermal decomposition of the precursor, in order to provide a commercially acceptable CVD, ALD or digital CVD process. In still another alternative, a liquid delivery system may be utilized wherein the precursor is stored in and delivered from an ionic liquid.

In liquid delivery formulations, metal source precursors that are liquids may be used in neat liquid form, or liquid or solid metal source precursors may be employed in solvent formulations containing same. Thus, metal source precursor formulations of the invention may include solvent component(s) of suitable character as may be desirable and advantageous in a given end use application to form metals on a substrate.

Suitable solvents may for example include alkane solvents (e.g., hexane, heptane, octane, nonane, decane and pentane), aryl solvents (e.g., benzene or toluene), amines (e.g., triethylamine, tert-butylamine), imines and carbodiimides (e.g., N,N'-diisopropylcarbodiimide). The utility of specific solvent compositions for particular metal source precursors may be readily empirically determined, to select an appropriate single component or multiple component solvent medium for the liquid delivery vaporization and transport of the specific metal source precursor that is employed. In some embodiments, oxygenated species such as alcohols, ethers, ketones, aldehydes, and other species that might serve as coordinating species, can be employed.

In specific embodiments, the solvent utilized in the source reagent solutions of the invention are selected from among aliphatic hydrocarbons, aromatic hydrocarbons, ethers, esters, nitrites, and alcohols. The solvent component of the solution can comprise a solvent selected from the group consisting of: glyme solvents having from 1 to 20 ethoxy —(C2H40)— repeat units; C2-C12 alkanols, organic ethers selected from the group consisting of dialkyl ethers comprising Cj-Cg alkyl moieties, C4-C8 cyclic ethers; C12-C60crown-04—O20 ethers wherein the prefixed C, range is the number i of carbon atoms in the ether compound and the suffixed O, range is the number i of oxygen atoms in the ether compound; C6-C12 aliphatic hydrocarbons; C6-C18 aromatic hydrocarbons; organic esters; organic amines; and polyamines.

In another aspect of the invention, a solid delivery system may be utilized, for example, using the ProE-Vap® solid delivery and vaporizer unit (commercially available from ATMI, Inc., Danbury, Conn., USA).

In another aspect of the invention, a liquid delivery system may be utilized, for example using the NOWTrak® system (commercially available from ATMI, Inc., Danbury, Conn., USA). In still another aspect of the invention, the packaging utilized in liquid delivery employing the NOWTrak® system includes a disposable liner adapted to hold the liquid precursor composition. Exemplary systems include, but are not limited to, those set forth in U.S. Pat. No. 6,879,876, filed Jun. 13,2001 andissuedApr. 12,2005 and titled "Liquid handling system with electronic information storage"; U.S. patent application Ser. No. 10/139,104, filed May 3,2002, published Jan. 2,2003 as U.S. Patent Application Publication No. 2003/ 0004608 and titled "Liquid handling system with electronic 5 information storage"; U.S. patent application Ser. No. 10/742,125, filed Dec. 19, 2003, published Sep. 2, 2004 as U.S. Patent Application Publication No. 2004/0172160 and titled "Secure Reader System"; and U.S. Provisional Patent Application No. 60/819,681 filed Jul. 10,2006 entitled "Fluid 10 storage vessel management systems and methods employing electronic information storage," the benefit of priority of which was claimed in U.S. Non-Provisional patent application Ser. No. 12/307,957 filed Jan. 8, 2009 and published on Jan. 7,2010asU.S. Patent Application Publication No. 2010/ 15 0004772, all of which are hereby incorporated by reference in their respective entireties. selected from hydrocarbyl (e.g., C^C^ alkyl such as C1 alkyl (i.e., methyl), C2 alkyl (i.e., ethyl), C3 alkyl (e.g., n-propyl or iso-propyl), C4 alkyl (e.g., n-butyl, iso-butyl, t-butyl), C5 alkyl (e.g., n-pentyl, iso-pentyl), C8 alkyl (e.g., octyl), C9 alkyl (e.g., nonyl), C10 alkyl, C11; alkyl, C12 alkyl), alkenyl 5 (e.g., C1-C12 alkenyl), and aryl and any combination or subcombination thereof), hydrogen, silyl, hydrazyl (for example Me2NNH—) and alkylamino (for example Me2N—, MeHN—, etc.).

Other non-limiting aspects, features and advantages of the present invention will be more fully apparent from the ensuing disclosure and appended claims. 20

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 includes the XH & 13C NMRs of [(Bu*NC(NMe2) NEt)Ta(NMe2)4]. The top plot is the 13C NMR. The bottom 25 plot is the XH NMR.

FIG. 2 is an STA (simultaneous thermal analysis) diagram illustrating comparison of STA data among DEMAT (5.15 mg), [(Bu*NC(NMe2)NEt)Ta(NMe2)4] (9.56 mg) and (NMe2)4Ta(ri2-Pr'NC(NMe2)NPr') (10.57 mg). 30

FIG. 3 is an ORTEP diagram of [(BuT^C(NMe2)NEt)Ta (NMe2)4].

FIG. 4 is a packing diagram of [(BuTsfC(NMe2)NEt)Ta (NMe2)4] along the c axis.

FIG. 5 is a schematic illustration of a semiconductor device 35 structure according to one embodiment of the present invention, featuring an amorphous Ta-containing barrier film and copper metallization.

One or more embodiments of the present invention relate in various aspects to precursor compositions (and vapor, gas or plasma forms thereof) useful for forming tantalum-contain- 45 ing films (e.g., barrier layers or films). Other embodiments relate to tantalum-containing films, such as may be employed as barrier layers in semiconductor devices utilizing copper metallization, as well as to other semiconductor device structures including tantalum-containing films. 50

As used herein, the term "semiconductor device structures" is intended to be broadly construed to include microelectronic devices, products, components, assemblies and subassemblies that include a semiconductor material as a functional material therein. Illustrative examples of semicon- 55 ductor device structures include, without limitation, resistcoated semiconductor substrates, flat-panel displays, thinfilm recording heads, microelectromechanical systems (MEMS), and other advanced microelectronic components. The semiconductor device structure may include patterned 60 and/or blanketed silicon wafers, flat-panel display substrates or fluoropolymer substrates. Further, the semiconductor device structure may include mesoporous or microporous inorganic solids.

"Alkyls" as used herein include, but are not limited to, 65 methyl, ethyl, propyl, isopropyl, butyl, s-butyl, t-butyl, pentyl and isopentyl and the like. "Aryls" as used herein includes

hydrocarbons derived from benzene or a benzene derivative that are unsaturated aromatic carbocyclic groups of from 6 to 10 carbon atoms. The aryls may have a single or multiple rings. The term "aryl" as used herein also includes substituted aryls. Examples include, but are not limited to phenyl, naphthyl, xylene, phenylethane, substituted phenyl, substituted naphthyl, substituted xylene, substituted phenylethane and the like. "Cycloalkyls" as used herein include, but are not limited to cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and the like. In all chemical formulae herein, a range of carbon numbers will be regarded as specifying a sequence of consecutive alternative carbon-containing moieties, including all moieties containing numbers of carbon atoms intermediate the endpoint values of carbon number in the specific range as well as moieties containing numbers of carbon atoms equal to an endpoint value of the specific range, e.g., C1 -C6, is inclusive of C1; C2, C3, C4, C5 and C6, and each of such broader ranges may be further limitingly specified with reference to carbon numbers within such ranges, as sub-ranges thereof. Thus, for example, the range Cj-Cg would be inclusive of and can be further limited by specification of subranges such as C1-C3, Cj-C^ C2-C6, C4-C6, etc. within the scope of the broader range.

As used herein, the term "film" refers to a layer of deposited material having a thickness below 1000 micrometers, e.g., from such value down to atomic monolayer thickness values. In various embodiments, film thicknesses of deposited material layers in the practice of the invention may for example be below 100, 10, or 1 micrometers, or in various thin film regimes below 200, 100, or 50 nanometers, depending on the specific application involved. As used herein, the term "thin film" means a layer of a material having a thickness below 1 micrometer.

It is noted that as used herein and in the appended claims, the singular forms "a", "and", and "the" include plural referents unless the context clearly dictates otherwise.

The invention, as variously described herein in respect of features, aspects and embodiments thereof, may in particular implementations be constituted as comprising, consisting, or consisting essentially of, some or all of such features, aspects and embodiments, as well as elements and components thereof being aggregated to constitute various further implementations of the invention.

One or more embodiments of the present invention relate to a class of precursors selected from among precursors of Formula I below:

As used herein, the designation of organo substituents by 10 reference to carbon numbers, includes ranges as well as subranges within the ranges identified by end-point carbon numbers, and such sub-ranges maybe specified, e.g., as including one of such end-point carbon numbers in such a sub-range, or as including carbon numbers greater than the lower end-point 15 carbon number and less than the upper end-point carbon number of the range, to constitute various sub-ranges in the various specific embodiments of the invention. Alkyl groups may be branched or unbranched.

The precursors of Formula I (described herein) are useful 20 for forming tantalum-containing films, e.g., involving CVD and ALD of tantalum nitride and Ta metal films. These precursors also have utility as low temperature deposition precursors for forming Ta2Os and other Ta oxide films, e.g., in the fabrication of capacitors such as back-end capacitors. 25

These novel complexes may be readily purified, and their solution behavior in solvent media employed for liquid delivery processes, e.g., for CVD or ALD of Ta, TaN or Ta2Os films is superior to that of PDMAT [Ta(NMe2)5], PEMAT [Ta (NEtMe)5], etc. 30

The precursors of Formula I may be usefully employed for deposition of Ta-containing material on substrates, including, without limitation, deposition of Ta, TaN, Ta2Os, TaSiN, BiTa04, etc. The Ta-containing material may be deposited on the substrate in any suitable manner, with deposition pro- 35 cesses such as CVD and ALD sometimes being preferred. Depending on the substituents employed, the Formula I precursors may also be deposited by solid delivery techniques, e.g., in which the precursor is volatilized from a solid form under suitable temperature and pressure, e.g., vacuum condi- 40 tions.

The CVD process may be carried out in any suitable manner, for example, with the volatilized precursor being conveyed to a CVD reactor for contact with a heated substrate, e.g., a silicon wafer-based structure, or other microelectronic 45 device substrate. In such process, the volatilized precursor may be directed to the CVD reactor in neat form, or, more typically, in a carrier gas stream, which may include inert gas, plasma, oxidant, reductant, co-deposition species, and/or the like. 50

The CVD process may be carried out by liquid delivery processing, for example, in which the Ta precursor is dissolved or suspended in a solvent medium, which may include a single solvent or multi-solvent composition, as appropriate to the specific deposition application involved. Suitable sol- 55 vents for such purpose include any compatible solvents that are consistent with liquid delivery processing, as for example, hydrocarbon solvents, etc., with a suitable solvent for the specific deposition application being readily determinable within the skill of the art based on the disclosure herein. 60

The precursors of Formula I have particular utility as CVD or ALD precursors for deposition of thin films of TaN and TaSiN as barriers in integrated circuits, e.g., integrated circuitry including dielectric material and copper metallization.

The precursors of Formula I, and Formula II (i.e., 65 M(NR3R4)5; M=Ta or as described herein; R3 and R4 are as described herein) also may have particular utility as CVD or

8

ALD precursors for low temperature deposition of thin films of high k capacitor materials such as Ta2Os and BiTa04.

The precursors of Formula I may also have particular utility as CVD or ALD precursors for deposition of Ta containing metal films as barriers in integrated circuits.

Various embodiments of the present invention include a class of precursors selected from among precursors of Formula I described above. Additionally, according to one or more embodiments of the present invention, R1, R2, R3 and R4 can be the same as or different from one another, and each is independently selected from hydrocarbyl substituents including alkyl, arylalkyl, alkaryl, alkenyl, alkenylaryl, arylalkenyl, allyl, hydrogen, silyl, hydrazyl (for example, Me2NNH—) and alkylamino (for example, Me2N—, MeHN—, etc.). etc. that are optionally further substituted with one or more heteroatoms such as N, S, and O and/or with halo substituents and any combination or sub-combination thereof, and providing functionality that is sterically and chemically appropriate to the use of the composition as a precursor for forming tantalum-containing films and materials—as described herein.

The precursors of Formula I have utility for CVD and ALD of Ta carbide and Ta metal films, as well as for low temperature deposition of TaN, Ta2Os and other Ta-related oxide films for use in capacitor fabrication.

The precursors of Formula I can be synthesized by Scheme 1 or Scheme la below:

In such synthetic schemes, R1, R2, R3, and R4 are as described herein and M is tantalum.

The Formula I precursors are thermally stable and stable in solution. TheR1, R2, R3, and R4 ligands may be appropriately selected for the specific deposition application employed, e.g., for CVD or ALD deposition processing to form the desired Ta-containing material on the deposition substrate, within the skill of the art—based on the disclosure herein. The Formula I precursors are readily purified, and their solution behavior in solvent media may be suitably employed for liquid delivery processes, e.g., for CVD or ALD of Ta, TaN or Ta2Os films.

The precursors of Formula I have utility as CVD or ALD precursors for deposition of thin films of TaN and TaSiN as barriers in integrated circuits, e.g., integrated circuitry including dielectric material and copper metallization.

The precursors of Formula I also have particular utility as CVD or ALD precursors for low temperature deposition of thin films of high k capacitor materials such as Ta2Os and BiTaCX.