Method of forming high-k dielectric films based on novel titanium, zirconium, and hafnium precursors and their use for semiconductor manufacturing

Abstract

A method of forming on at least one support at least one metal containing dielectric films having the formula (M11-a M2a) Ob Nc, wherein: 0≦a<1, 01 and M2 being metals Hf, Zr or Ti using precursors with pentadienyl ligands and/or cyclopentadienyl ligands.

Description

This application is a 371 of International PCT Application PCT/EP2006/062893, filed Jun. 2, 2006.

The invention relates to a method of forming high-k dielectric films such as hafnium or zirconium oxides or oxynitrides and their use for manufacturing semi-conductors.

BACKGROUND

With the shrink of the critical dimensions of the future generation of semi-conductor devices, the introduction of new materials, especially having high dielectric constant, is required. In CMOS architectures, high-k dielectrics are required to replace SiO₂ which reaches its physical limits, having typically a SiO₂ equivalent thickness of about 1 nm.

Similarly, high-k dielectrics are required in Metal-Insulator-Metal architectures for RAM applications. Various metal compositions have been considered to fulfill both the materials requirements (dielectric constant, leakage current, crystallisation temperature, charge trapping) and the integration requirements (thermal stability at the interface, dry etching feasibility . . . ).

The Group IV based materials, such as HfO₂, HfSiO₄, ZrO₂, ZrSiO₄, HfZrO₄, HfLnO_x (Ln being selected from the group comprising scandium, yttrium and rare-earth elements) are among most promising materials. Furthermore, Group IV metals composition can also be considered for electrode and/or Cu diffusion barrier applications, such as TiN for mid-gap metal gate and MIM RAM, HfN, ZrN, HfSi, ZrSi, HfSiN, ZrSiN, TiSiN . . . .

Deposition processes of such thin films with reasonable throughput and acceptable purity are vapor phase deposition techniques, such as MOCVD (Metal-organic Chemical Vapor Deposition) or ALD (Atomic Layer Deposition). Such deposition processes require metal precursors that must fulfill drastic requirements for a proper industrial use.

It is known from Kim et al., Electrochem Soc Proceedings 2005-05, 397, 2005, to use HfCl₄ for the deposition of HfO₂ by ALD. However, some by-products generated during the deposition process, such as HCl or Cl₂, can cause surface/interface roughness that can be detrimental to the final properties. Other possible byproducts, depending on the oxygen source used, may be hazardous. For instance, OCl₂, through the OCl fragment by QMS, has been detected as a byproduct of the reaction between HfCl₄ and O₃. Moreover, in the case of high-k oxide, Cl or F impurities are detrimental to the final electrical properties and Cl and F-containing precursors are therefore not preferred.

Triyoso et al. in J. Electrochem. Soc. 152 (3) G203-G209 (2005), Chang et al. in Electrochem. Solid. State Let., 7 (6) F42-F44 (2004), studied the use of Hf(OtBu)₄ for HfO₂ MOCVD and ALD, respectively. Williams et al. have evaluated Hf(mmp)₄ and Hf(OtBu)₂(mmp)₂ for MOCVD of HfO₂. In WO2003035926, Jones et al. disclose solid Ti, Hf, Zr and La precursors improved with donor functionalized alkoxy ligand (1-methoxy-2-methyl-2-propanolate[OCMe₂CH₂OMe, mmp]) which helps inhibiting oligomerisation of Zr and Hf alkoxide compounds and increasing their stability towards moisture. However, all those alkoxide precursors have the drawback not to enable self-limited deposition in ALD process.

Alkylamides precursors such as Hf(NEtMe)₄, Hf(NMe₂)₄, Hf(NEt₂)₄ . . . have been widely disclosed in the literature such as by Senzaki et al in J. Vac. Sci. Technol. A 22(4) July/August 2004, Haussmann et al. in Chem. Mater. 2002, 14, 4350-4353, Kawahara et al. in J. Appl. Phys., Vol 43, No. 7A, 2004, pp 4129-4134, Hideaki et al. in JP2002093804, Metzner et al. in U.S. Pat. No. 6,858,547, Dip et al. in US20050056219. Group IV alkylamides are both suitable for ALD and MOCVD processes. Furthermore, some are liquid at room temperature (TDEAH and TEMAH) and of sufficient volatility, and they allow self-limited ALD at low temperature for a limited thermal budget process. However, Group IV alkylamides have several drawbacks:

• • they may decompose during the distribution to some extent leading to a possible clogging of the feeding line or the vaporizer,
  • they may generate particles during deposition,
  • they may entail non-uniform compositions during deep trenches deposition processes,
  • they only allow a narrow self-limited ALD temperature window, hence reducing the process window.

Carta et al. disclose in Electrochem Soc Proceedings, 260, 2005-09, 2005 the use of bis(cyclopentadienyl)bisdimethyl hafnium and several authors (Codato et al., Chem Vapor Deposition, 159, 5, 1995; Putkonen et al., J Mater Chem, 3141, 11, 2001; Niinisto et al., Langmuir, 7321, 21, 2005) disclose the use of bis(cyclopentadienyl)bisdimethyl zirconium, which allow an efficient ALD deposition process with an ALD window up to 400° C. and an achievement of films with less than 0.2% C in optimized conditions with H₂O as co-reactant. However, HfCp₂Me₂ and ZrCp₂Me₂ both have the drawback of being solid products at room temperature (HfCp₂Me₂ melting point is 57.5° C.). This makes inconvenient their use by IC makers.

In U.S. Pat. No. 6,743,473, Parkhe et al. disclose the use of (Cp(R)_n)_xMH_y-x, to make a metal and/or a metal nitride layer, where M is selected from tantalum, vanadium, niobium and hafnium, Cp is cyclopentadienyl, R is an organic group. Only examples of tantalum and niobium cyclopentadienyl compounds are disclosed. However, no liquid precursor or a precursor having a melting point lower than 50° C. is disclosed.

Today, there is a need for providing liquid or low melting point (<50° C.) group IV precursor compounds, and in particular Hf and Zr compounds, that would allow simultaneously:

• • proper distribution (physical state, thermal stability at distribution temperatures),
  • wide self-limited ALD window,
  • deposition of pure films either by ALD or MOCVD.

DISCLOSURE

According to the invention, certain cyclopentadienyl or pentadienyl based group IV metal-organic precursors have been found suitable for the deposition of Group IV metal containing thin films by either ALD or MOCVD processes and have the following advantages:

• • They are liquid at room temperature or having a melting point lower than 50° C.,
  • They are thermally stable to enable proper distribution (gas phase or direct liquid injection) without particles generation,
  • They are thermally stable to allow wide self-limited ALD window, 4) allowing deposition of a variety of Group IV metals containing films, including ternary or quaternary materials, by using one or a combination of co-reactants (selected from the group comprising of H₂, NH₃, O₂, H₂O, O₃, SiH₄, Si₂H₆, Si₃H₈, TriDMAS, BDMAS, BDEAS, TDEAS, TDMAS, TEMAS, (SiH₃)₃N, (SiH₃)₂O, TMA or an aluminum-containing precursor, TBTDET, TAT-DMAE, PET, TBTDEN, PEN, lanthanide-containing precursors such as Ln(tmhd)₃ . . . ).

According to the invention, there is provided a method of forming on at least one substrate at least one metal containing dielectric film having the formula (M¹_1-a M²_a) O_b N_c, wherein:

• • 0≦a<1
  • 0<b≦3, preferably 1.5≦b≦2.5
  • 0≦c≦1, preferably 0≦c≦0.5
  • M¹ and M² being metals

said method comprising the steps of:

• • (a) providing a substrate into a reactor
  • (b) introducing into said reactor at least one metal containing precursor having the formula:(R_yOp)_x(R_tCp)_zM¹R′_4-x-z wherein:
  • M¹=Hf, Zr and/or Ti;
  • (R_yOp) represents one pentadienyl (Op) ligand, substituted or not, with y R substituents in any position on Op;
  • (R_tCp) represents one cyclopentadienyl (Cp) ligand, substituted or not with t R substituants in any position on Cp;
  • Each R substituting a pentadienyl or each R substituting a cyclopentadienyl is a ligand independently selected from the group consisting of Cl, C1-C4 linear or branched, alkyl, alkylamides, alkoxide, alkylsilylamides, amidinates, carbonyl, each R being similar to or different from other R substituting the pentadienyl and other R substituting the cyclopentadienyl;
  • Each R′ is a ligand independently selected from the group consisting of H, Cl, C1-C4 linear or branched, alkyl, alkylamides, alkoxide, alkylsilylamides, amidinates, carbonyl, each R′ being similar or different.
  • x is an integer representing the number of pentadienyl ligands, substituted or not;
  • z is an integer representing the number of cyclopentadienyl ligands, substituted or not;
  • y is an integer representing the number of substituants on each Op, and is independent selected for each Op;
  • t is an integer representing the number of substituants on each Cp, and is independent selected for each Cp;
  • 0≦x≦3, preferably x=0 or 1;
  • 0≦z≦3, preferably z=2;
  • 0≦y≦7, preferably y=2 and in this case each R is a methyl group;
  • 0≦t≦5, preferably t=1 and R is a methyl group;
  • Unspecified substituents to Cp or Op ligands are H by default.
  • (c) optionally introducing at least one M² containing precursor, M² being selected from the group essentially consisting of Mg, Ca, Zn, B, Al, In, Lanthanides (Sc, Y, La and rare earths), Si, Ge, Sn, Ti, Zr, Hf, V, Nb, Ta;
  • (d) providing at least one oxygen containing and/or nitrogen containing fluid into said reactor;
  • (e) reacting said at least one metal containing precursor with said at least one oxygen containing and/or nitrogen containing fluid;
  • (f) depositing said (M¹_1-a M²a) O_b N_c, film onto said substrate at a temperature comprised between 100° C. to 500° C., preferably between 150° C. and 350° C.,provided that when a=0, b=2, c=0, x=0, z=2, at least one t on at least one Cp is different from zero.

The oxygen containing fluids shall be preferably selected from the group consisting of O₂, O₃, H₂O, H₂O₂, oxygen-containing radicals such as O. or OH. and mixtures thereof, while the nitrogen-containing fluids shall be selected from the group consisting of N₂, NH₃, hydrazine and its alkyl or aryl derivatives, nitrogen-containing radicals such as N., NH., NH₂. and mixtures thereof.

According to one embodiment when both nitrogen and oxygen are needed, the oxygen and nitrogen-containing fluids may be selected from the group consisting of NO, NO₂, N₂O, N₂O₅, N₂O₄ and mixtures thereof, (selecting one of those fluids automatically generate an oxynitride layer, with a certain ration of N/O molecules. If the certain ratio is not appropriate, then another nitrogen containing fluid and/or another oxygen containing fluid is needed.

To carry out the process of the invention, the pressure shall be comprised between 1 Pa and 100000 Pa, preferably between 25 Pa and 1000 Pa.

The various reactants can be introduced into the reactor either simultaneously (chemical vapor deposition), sequentially (atomic layer deposition) or different combinations thereof (one example is to introduce e.g. the two metal sources together in one pulse and the oxygen gas in a separate pulse (modified atomic layer deposition); another example is to introduce oxygen continuously and to introduce metal source by pulse (pulsed chemical vapor deposition)).

According to another embodiment the method according to the invention may further comprise the step of (g) providing at least one metal containing precursor containing at least one of the following precursors: M¹(NMe₂)₄, M¹(NEt₂)₄, M¹(NMeEt)₄, M¹(mmp)₄, M¹(OtBu)₄, M¹(OtBu)₂(mmp)₂ and mixtures thereof.

Preferably, the at least one metal containing precursor introduced in step b) defined here above shall have a melting point below 50° C., preferably below 35° C. while more preferably the at least one metal containing precursor shall be liquid at room temperature.

The method according to the invention may also further comprises the step of:

• • (h) mixing together at least two different metal containing precursors A and B to provide a precursor mixture, A being (R_yOp)_x(R_tCp)_zM¹R′_4-x-z and B being selected from the group consisting of (R_yOp)_x(R_tCp)_zM¹R′_4-x-z, M¹(NMe₂)₄, M¹(NEt₂)₄, M¹(NMeEt)₄, M¹(mmp)₄, M¹(OtBu)₄, M¹(OtBu)₂(mmp)₂ and mixtures thereof, and
  • (i) providing said metal precursor mixture into said reactor.

According to an alternative method of the invention, step (h) and (i) as defined above are carried out instead of step (b).

According to another embodiment of the invention, to form an M¹oxyde containing film wherein a=0, b being equal to about 2 and c=0, the metal containing precursor of steps (b) and/or (h) is selected from the group consisting of: HfCp₂Cl₂, Hf(MeCp)₂Me₂, HfCp(MeCp)Cl₂, Hf(MeCp)₂Cl₂, HfCp(MeCp)Me₂, Hf(EtCp)(MeCp)Me₂, Hf(EtCp)₂Me₂, Hf(MeCp)₂(CO)₂, ZrCP₂Cl₂, Zr(MeCp)₂Me₂, ZrCp(MeCp)Cl₂, Zr(MeCp)₂Cl₂, ZrCp(MeCp)Me₂, Zr(EtCp)(MeCp)Me₂, Zr(EtCp)₂Me₂, Zr(MeCp)₂(CO)₂ and mixtures thereof.

According to still another embodiment of the invention, to form an M¹oxynitride-containing dielectric film wherein a=0, 1.5≦b≦2.5 and 0<c≦0.5, the metal containing precursor of step (b) and/or (h) shall be selected from the group consisting of HfCP₂Cl₂, Hf(MeCp)₂Me₂, HfCp(MeCp)Cl₂, Hf(MeCp)₂Cl₂, HfCp(MeCp)Me₂, Hf(EtCp)(MeCp)Me₂, Hf(EtCp)₂Me₂, Hf(MeCp)₂(CO)₂, ZrCP₂Cl₂, Zr(MeCp)₂Me₂, Zr(MeCp)₂Cl₂, ZrCp(MeCp)Me₂, Zr(EtCp)(MeCp)Me₂, Zr(EtCp)₂Me₂, Zr(MeCp)₂(CO)₂ and mixture thereof.

According to another embodiment of the invention to form an M¹M² Oxide containing dielectric film wherein 0≦a<1 and c=0, the metal containing precursor of step (b) and/or (h) shall be selected from the group consisting of HfCP₂Cl₂, Hf(MeCp)₂Me₂, HfCp(MeCp)Cl₂, Hf(MeCp)₂Cl₂, HfCp(MeCp)Me₂, Hf(EtCp)(MeCp)Me₂, Hf(EtCp)₂Me₂, Hf(MeCp)₂(CO)₂, ZrCP₂Cl₂, Zr(MeCp)₂Me₂, ZrCp(MeCp)Cl₂, Zr(MeCp)₂Cl₂, ZrCp(MeCp)Me₂, Zr(EtCp)(MeCp)Me₂, Zr(EtCp)₂Me₂, Zr(MeCp)₂(CO)₂, the M² containing precursor of step (c) being introduced into the reactor, said precursor being preferably selected from the group consisting of Si, Mg, lanthanides (i.e. Sc, Y and rare earths) and/or Ta.

According to another different embodiment of the invention, the M² containing precursor is selected from the group consisting of disiloxane, trisilylamine, disilane, trisilane, a alkoxysilane SiH_x(OR¹)_4-x, silanol Si(OH)_x(OR¹)_4-x(preferably Si(OH)(OR¹)₃; more preferably Si(OH)(OtBu)₃), aminosilane SiH_x(NR¹R²)_4-x (where x is comprised between 0 and 4; R¹ and R² are independently H or a C1-C6 carbon chain, either linear, branched or cyclic; preferably TriDMAS SiH(NMe₂)₃; BTBAS SiH₂(NHtBu)₂); BDEAS SiH₂(NEt₂)₂) and mixtures thereof (or their germanium equivalents), trimethylaluminum, dimethylaluminum hydride, alkoxyalane AlRⁱ_x(OR′)_3-x (where x is comprised between 0 and 4; each Rⁱ is independently H or a C1-C6 carbon chain, either linear, branched or cyclic; preferably AlR¹R²(OR′), with R¹ and R² are independently H or a C1-C6 carbon chain, either linear, branched or cyclic, most preferably AlMe₂(OiPr)), amidoalane AlRⁱ_x(NR′R″)_3-x (where x is comprised between 0 and 3; each Rⁱ is independently H or a C1-C6 carbon chain, either linear, branched or cyclic), Ta(OMe)₅, Ta(OEt)₅, Ta(OR¹)₄(O—C(R²)(R³)—CH₂—OR⁴) (each Rⁱ is independently H or a C1-C6 carbon chain, either linear, branched or cyclic, preferably TAT-DMAE Ta(OEt)(OCMe₂CH₂—OMe)), Ta(OR¹)₄(O—C(R²)(R³)—CH₂—N(R⁴)(R⁵)) (each Rⁱ is independently H or a C1-C6 carbon chain, either linear, branched or cyclic, Ta(NMe₂)₅, Ta(NEt₂)₄, Ta(NEt₂)₅, Ta(═NR¹)(NR²R³)₃ (each R¹, R² and R³ are independently H or a C1-C6 carbon chain, either linear, branched or cyclic and where the amino ligand can have different substituant), Nb(OMe)₅, Nb(OEt)₅, Nb(OR¹)₄(O—C(R²)(R³)—CH₂—OR⁴) (each Rⁱ is independently H or a C1-C6 carbon chain, either linear, branched or cyclic, preferably NBT-DMAE Nb(OEt)(OCMe₂CH₂—OMe)), Nb(OR¹)₄(O—C(R²)(R³)—CH₂—N(R⁴)(R⁵)) (each R¹ is independently H or a C1-C6 carbon chain, either linear, branched or cyclic, Nb(NMe₂)₅, Nb(NEt₂)₄, Nb(NEt₂)₅, Nb(═NR¹)(NR²R³)₃ (each R¹, R² and R³ are independently H or a C1-C6 carbon chain, either linear, branched or cyclic and where the amino ligand can have different substituent), a lanthanide metal source (Sc, Y, La, Ce, Pr, Nd, Gd . . . ), a source with at least one β-diketonate ligand, such as having the form of Ln(—O—C(R¹)—C(R²)—C(R³)—O—)(—O—C(R⁴)—C(R⁵)—C(R⁶)—O—)(—O—C(R⁷)—C(R⁸)—C(R⁹)—O—) where each Rⁱ is independently H or a C1-C6 carbon chain, either linear, branched or cyclic), or of the form of a cyclopentadienyl lanthanide Ln(R¹Cp)(R²Cp)(R³CP) (where each Rⁱ is independently H or a C1-C6 carbon chain, either linear, branched or cyclic), Ln(NR¹R²)(NR³R⁴)(NR⁵R⁶) (where each Rⁱ is bonded to nitrogen and is independently H or a C1-C6 carbon chain, either linear, branched or cyclic or an alkylsilyl chain of the form SiR⁷R⁸R⁹ where each Rⁱ is bonded to silicon and is independently H or a C1-C4 carbon chain, either linear, branched or cyclic), a divalent metal A (preferably Mg, Ca, Zn) of the form A(—O—C(R¹)—C(R²)—C(R³)—O—)(—O—C(R⁴)—C(R⁵)—C(R⁶)—O—) (where each Rⁱ is independently H or a C1-C6 carbon chain, either linear, branched or cyclic) or of the form of a cyclopentadienyl lanthanide A(R¹Cp)(R²Cp) (where each Rⁱ is independently H or a C1-C6 carbon chain, either linear, branched or cyclic).

According to an embodiment of the invention, to form an M¹M² oxynitride containing dielectric film wherein 0≦a<1 and 0<c≦0.5, the metal containing precursor of step (b) and/or (h) shall be selected from the group consisting of HfCP₂Cl₂, Hf(MeCp)₂Me₂, HfCp(MeCp)Cl₂, Hf(MeCp)₂Cl₂, HfCp(MeCp)Me₂, Hf(EtCp)(MeCp)Me₂, Hf(EtCp)₂Me₂, Hf(MeCp)₂(CO)₂, ZrCP₂Cl₂, Zr(MeCp)₂Me₂, ZrCp(MeCp)Cl₂, Zr(MeCp)₂Cl₂, ZrCp(MeCp)Me₂, Zr(EtCp)(MeCp)Me₂, Zr(EtCp)₂Me₂, Zr(MeCp)₂(CO)₂, the M² containing precursor of step (c) being introduced into the reactor, said M² precursor being preferably selected from the group consisting of Si, Mg, lanthanides (i.e. Sc, Y and rare earths) and/or Ta, and wherein in step (d) at least one oxygen containing precursor and at least one nitrogen containing precursor is introduced into the reactor.

Preferably, when M¹M² oxynitride are deposited, the M² containing precursor is selected from the group consisting of disiloxane, trisilylamine, disilane, trisilane, a alkoxysilane SiH_x(OR¹)_4-x, a silanol Si(OH)_x(OR¹)_4-x (preferably Si(OH)(OR¹)₃, more preferably Si(OH)(OtBu)₃ an aminosilane SiH_x(NR¹R²)_4-x (where x is comprised between 0 and 4; R¹ and R² are independently H or a C1-C6 carbon chain, either linear, branched or cyclic; preferably TriDMAS SiH(NMe₂)₃, BTBAS SiH₂(NHtBu)₂); BDEAS SiH₂(NEt₂)₂) and mixtures thereof (or their germanium equivalents), trimethylaluminum, dimethylaluminum hydride, an alkoxyalane AlRⁱ_x(OR′)_3-x (where x is comprised between 0 and 4; R¹ and R² are independently H or a C1-C6 carbon chain, either linear, branched or cyclic; preferably AlR¹R²(OR′), most preferably AlMe₂(OiPr)), an amidoalane AlRⁱ_x(NR′R″)_3-x (where x is comprised between 0 and 4; R¹ and R² are independently H or a C1-C6 carbon chain, either linear, branched or cyclic), Ta(OMe)₅, Ta(OEt)₅, Ta(OR¹)₄(O—C(R²)(R³)—CH₂—OR⁴) (each Rⁱ is independently H or a C1-C6 carbon chain, either linear, branched or cyclic, preferably TAT-DMAE Ta(OEt)(OCMe₂CH₂—OMe)), Ta(OR¹)₄(O—C(R²)(R³)—CH₂—N(R⁴)(R⁵)) (each Rⁱ is independently H or a C1-C6 carbon chain, either linear, branched or cyclic, Ta(NMe₂)₅, Ta(NEt₂)₄, Ta(NEt₂)₅, Ta(═NR¹)(NR²R³)₃ (each R¹ and R² are independently H or a C1-C6 carbon chain, either linear, branched or cyclic and where the amino ligand can have different substituant), Nb(OMe)₅, Nb(OEt)₅, Nb(OR¹)₄(O—C(R²)(R³)—CH₂—OR⁴) (each R′ is independently H or a C1-C6 carbon chain, either linear, branched or cyclic, preferably NBT-DMAE Nb(OEt)(OCMe₂CH₂—OMe)), Nb(OR¹)₄(O—C(R²)(R³)—CH₂—N(R⁴)(R⁵)) (each Rⁱ is independently H or a C1-C6 carbon chain, either linear, branched or cyclic, Nb(NMe₂)₅, Nb(NEt₂)₄, Nb(NEt₂)₅, Nb(═NR¹)(NR²R³)₃ (each R¹, R² and R³ are independently H or a C1-C6 carbon chain, either linear, branched or cyclic and where the amino ligand can have different substituant), a lanthanide metal source (Sc, Y, La, Ce, Pr, Nd, Gd . . . ) source with at least one β-diketonate ligand, such as of the form Ln(—O—C(R¹)—C(R²)—C(R³)—O—)(—O—C(R⁴)—C(R⁵)—C(R⁶)—O—)(—O—C(R⁷)—C(R⁸)—C(R⁹)—O—) where each Rⁱ is independently H or a C1-C6 carbon chain, either linear, branched or cyclic), or of the form of a cyclopentadienyl lanthanide Ln(R¹Cp)(R²Cp)(R³CP) (where each Rⁱ is independently H or a C1-C6 carbon chain, either linear, branched or cyclic), Ln(NR¹R²)(NR³R⁴)(NR⁵R⁶) (where each Rⁱ is bonded to nitrogen and is independently H or a C1-C6 carbon chain, either linear, branched or cyclic or an alkylsilyl chain of the form SiR⁷R⁸R⁹ where each Rⁱ is bonded to silicon and is independently H or a C1-C4 carbon chain, either linear, branched or cyclic), a divalent metal A (preferably Mg, Ca, Zn) of the form A(—O—C(R¹)—C(R²)—C(R³)—O—)(—O—C(R⁴)—C(R⁵)—C(R⁶)—O—) (where each Rⁱ is independently H or a C1-C6 carbon chain, either linear, branched or cyclic) or of the form of a cyclopentadienyl lanthanide A(R¹Cp)(R²Cp) (where each Rⁱ is independently H or a C1-C6 carbon chain, either linear, branched or cyclic).

The invention also may generally relates to the use of (R_yOp)_x(R_tCp)_zM¹R′_4-x-z to make dielectric films e.g. for integrated circuits or Metal Insulator Metal (MIM) architectures for Random Access Memories.

According to still another aspect, the invention relates also to new precursors comprising composition for semi-conductor or RAM manufacture, said precursor having the formula:(R_yOp)_x(R_tCp)_zM¹R′_4-x-z wherein

• • M¹=Hf, Zr and/or Ti
  • (R_yOp) represents one pentadienyl (Op) ligand, substituted or not, with y R substituants in any position on Op;
  • (R_tCp) represents one cyclopentadienyl (Cp) ligand, substituted or not, with t R substituants in any position on Cp;
  • Each R substituting a pentadienyl or R substituting a cyclopentadienyl are organics independently selected from the group consisting of Cl, C1-C4 linear or branched, alkyl, alkylamides, alkoxide, alkylsilylamides, amidinates, carbonyl, each R_y or each R_t being similar to or different from other R_y or other R_t, respectively;
  • Each R′ is an organics independently selected from the group consisting of H, Cl, C1-C4 linear or branched, alkyl, alkylamides, alkoxide, alkylsilylamides, amidinates, carbonyl, each R′ being similar or different.
  • x is an integer representing the number of pentadienyl ligand, substituted or not
  • z is an integer representing the number of cyclopentadienyl ligand, substituted or not;
  • y is an integer representing the number of substituants on each Op, and is independent by selected for each Op;
  • t is an integer representing the number of substituants on each Cp, and is independent selected for each Cp;
  • 0≦x≦3, preferably x=0 or 1;
  • 0≦z≦3, preferably z=2;
  • 0≦y≦7, preferably y=2 and in this case each R is methyl;
  • 0≦t≦5, preferably t=1 and R is a methyl group;
  • Unspecified substituents to Cp or Op ligands are H by default;
  • All R′ are not simultaneously equal to H when x=0,provided that when a=0, b=2, c=0, x=0, z=2, at least one t on at least one Cp is different from 0.

According to another embodiment, such new precursor composition may further comprise a second metal containing precursor, different from the first metal precursor, said second metal containing precursor being selected from the group consisting of (R_yOp)_x(R_tCp)_zM¹R′_4-x-z, M¹(NMe₂)₄, M¹(NEt₂)₄, M¹(NEtMe)₄, M¹(mmp)₄, M¹(OtBu)₄, M¹ (OtBu)₂(mmp)₂ and mixtures thereof.

DETAILED DESCRIPTION

Example I

Deposition of Metal Oxide Film M¹O₂ with M¹ being Preferably Hafnium and Zirconium

The film to be deposited relates to the case where a=0, b is about 2 and c=0.

To make the deposition of such film on the surface of a wafer or in a deep trench to manufacture MIM structures for DRAM, one need to vaporize the M¹ metal source as defined in steps (b) and/or (h) here above into the reactor (preferably Hafnium or Zirconium), inject an oxygen source, preferably moisture, oxygen or ozone into said reactor, react the products at appropriate temperature (preferably between 150° C. and 350° C.) and pressure (preferably between 25 Pa and 1000 Pa) for the duration necessary to achieve either a thin film deposition on the substrate or to fill out deep trenches by ALD or pulse CVD process (sequential pulse injection of metal sources are necessary in order to allow regular deposition of the oxide in the trench to progressively fill out this trench and provide no voids in the dielectric film and therefore no defect in the capacitor dielectric film).

The dielectric film shall have the desired final composition (here essentially variations of the b value around 2 modifying the ratio of precursor to oxygen source).

It is possible to select the M¹ containing precursors from the three following options, a, b or c:

a) M¹ source is a molecule or a mixture of molecules having the formula (R_tCp)_zM¹R′_4-z, wherein:

• • M¹ is a group IV metal selected from the group consisting of Hf, Zr, Ti or mixture thereof.
  • z is an integer comprised between 1 and 3, preferably z=2.
  • t is an integer between 0 and 5, preferably t=1.
  • Cp is a cyclopentadienyl ligand. Each Cp comprises t substituents R
  • Each R substituting a cyclopentadienyl is a ligand independently selected from the group consisting of C1, C1-C4 linear or branched, alkyl, alkylamides, alkoxide, alkylsilylamides, amidinates, carbonyl, isonitrile, each R being similar to or different from other R substituting the cyclopentadienyl;
  • Each R′ is a ligand independently selected from the group consisting of H, Cl, C1-C4 linear or branched, alkyl, alkylamides, alkoxide, alkylsilylamides, amidinates, carbonyl, each R′ being similar or different from other R′.
  • When one or several Cp ligands are present in the molecule, the number of substituents on each Cp can be different, their substituents (R) can be different and in whatever position on each Cp.

The preferred molecule is M(RCp)₂Me₂. More preferably R is Me or Et, while the molecule is preferably selected from the group of molecules having melting point lower than 35° C., more preferably which is liquid or which can be easy liquefied for easy delivery.

• • Delivery of molecules in liquid form is usually carried out by bubbling an inert gas (N₂, He, Ar, . . . ) into the liquid and providing the inert gas plus liquid gas mixture to the reactor.
  • The formula of the molecule is shown below:

b) The M¹ metal source is a molecule or mixture of molecules having the general formula: (R_yOp)_x M¹R′_4-x, wherein:

• • M¹ is a group IV metal (Hf, Zr, Ti).
  • x is an integer comprised between 1 and 3, preferably, x=2.
  • y is an integer between 1 and 7. Preferentially y=2.
  • Op is a pentadienyl ligand. Each Op comprises y substituents R.
  • R and R′ are organic ligand independently selected from the group consisting of H, Cl, C1-C4 linear or branched, alkyl, alkylamides, alkoxide, alkylsilylamides, amidinates, carbonyl, isonitrile. If several Op ligands are present in the molecule, the number of substituents can be similar or different, their substituents (R) can be different and in whatever position. Each R substituting a pentadienyl may be similar or different from other R also substituting a pentadienyl, either the same or a different one. Each R′ may be similar or different from other R′. Each Op may comprise one or several R.
  • The molecule is preferably M¹(2,4-R₂OP)₂Me₂. More preferably R is Me (i.e. metal dimethyl bis(2,4-dimethylpentadienyl).
  • The molecule has a melting point lower than 50° C. The molecule has preferably a melting point lower than 35° C., i.e. which is liquid or can be easy liquefied for easy delivery.

The general formula of the molecule is:

with one or several (y times) R on each Op cycle.c) The M¹ metal source is a molecule or mixture of molecules having the general formula: (R_yOp)_x(R_tCp)_zM¹R′_4-x-z, wherein:

• • M¹ is a group IV metal (Hf, Zr, Ti).
  • x and z are integers comprised between 1 and 3, preferably x=1, and z=1.
  • y and t are integers between 1 and 7, preferably y=2 and t=1.
  • Cp is a cyclopentadienyl ligand. Each Cp comprises t substituents R.
  • Op is a pentadienyl ligand. Each Op comprises y substituents R.
  • Each R substituting a pentadienyl and each R substituting a cyclopentadienyl, and R′ are ligands independently selected from the group consisting of H, C1, C1-C4 linear or branched, alkyl, alkylamides, alkoxide, alkylsilylamides, amidinates, carbonyl, isonitrile. Each R substituting a pentadienyl may be similar or different from other R substituting a pentadienyl, (either on the same or on a different one), or a cyclopentadienyl. Each R substituting a cyclopentadienyl may be similar or different from other R substituting a cyclopentadienyl, (either the same or on a different one), or a pentadienyl. Each Op and/or Cp may have one or several R substituents. If several Op ligands are present in the molecule, the number of substituents can be similar or different, their substituents (R) can be different. The same applies for the substituents R on Cp.
  • The molecule is preferably M(RCp)(2,4-R₂Op)Me₂. More preferably R substituting the cyclopentadienyl and the R's substituting the pentadienyl are Me (i.e. metal dimethyl(2,4-dimethylpentadienyl)(methylcylopentadienyl)).
  • The molecule has preferably a melting point lower than 35° C., i.e. which is liquid or can be easy liquefied for easy delivery.

The general formula of the molecule is:

The oxygen source shall be preferably, without limitations, oxygen (O₂), oxygen radicals (for instance O. or OH.), such as radicals generated by a remote plasma system, ozone, NO, N₂O, NO₂, moisture (H₂O) and H₂O₂.

Regarding the deposition process by itself, the reactants can be introduced into the reactor simultaneously (chemical vapor deposition), sequentially (atomic layer deposition) or different combinations (one example is to introduce metal source and the other metal source together in one pulse and oxygen in a separate pulse [modified atomic layer deposition]; another option is to introduce oxygen continuously and/or to introduce the metal source by pulse (pulsed-chemical vapor deposition).

Example II

Deposition of Metal Oxynitride Films M¹ON with M¹ being Preferably Hafnium and Zirconium

The film deposited relates to the case where a=0 and b and c are different from zero.

All the information given in Example I is applicable in this Example II, except that nitrogen needs to be introduced into the reactor.

The nitrogen shall be selected from a nitrogen source selected from the group comprising nitrogen (N₂), ammonia, hydrazine and alkyl derivatives, N-containing radicals (for instance N., NH., NH₂.), NO, N₂O, NO₂ or the like.

Example III

Deposition of M¹M² Metal Oxide Films with M¹ being Preferably Hf or Zr and M² being Preferably Si or Al

The film deposited on the substrate in this example illustrates the case wherein a≠0, b≠0 and c=0.

All the information given in Example I are applicable in this Example III, except that a M² metal source is additionally needed.

The M² containing precursor is also introduced into the reactor to crate the M² source of metal. This M² containing precursor source shall be preferably:

a) a silicon (or germanium) source and is selected from, but not limited to, the group consisting of disiloxane, trisilylamine, disilane, trisilane, a alkoxysilane SiH_x(OR¹)_4-x, a silanol Si(OH)_x(OR¹)_4-x (preferably Si(OH)(OR¹)₃; more preferably Si(OH)(OtBu)₃ an aminosilane SiH_x(NR¹R²)_4-x (where x is comprised between 0 and 4; R¹ and R² are independently H or a C1-C6 carbon chain, either linear, branched or cyclic; preferably TriDMAS SiH(NMe₂)₃; BTBAS SiH₂(NHtBu)₂) BDEAS SiH₂(NEt₂)₂) and mixtures thereof (or their germanium equivalent); orb) an aluminum source selected from the group comprising trimethylaluminum, dimethylaluminum hydride, an alkoxyalane AlRⁱ_x(OR′)_3-x (where x is comprised between 0 and 4; R¹ and R² are independently H or a C1-C6 carbon chain, either linear, branched or cyclic; preferably AlR¹R²(OR′), most preferably AlMe₂(OiPr)), an amidoalane AlRⁱ_x(NR′R″)_3-x (where x is comprised between 0 and 4; R¹ and R² are independently H or a C1-C6 carbon chain, either linear, branched or cyclic) and mixtures thereof; orc) a tantalum (or niobium) source selected from the group comprising Ta(OMe)₅, Ta(OEt)₅, Ta(OR¹)₄(O—C(R²)(R³)—CH₂—OR⁴) (each Rⁱ is independently H or a C1-C6 carbon chain, either linear, branched or cyclic, preferably TATDMAE Ta(OEt)(OCMe₂CH₂—OMe)), Ta(OR¹)₄(O—C(R²)(R³)—CH₂—N(R⁴)(R⁵)) (each Rⁱ is independently H or a C1-C6 carbon chain, either linear, branched or cyclic, Ta(NMe₂)₅, Ta(NEt₂)₄, Ta(NEt₂)₅, Ta(═NR¹)(NR²R³)₃ (each R¹ and R² are independently H or a C1-C6 carbon chain, either linear, branched or cyclic and where the amino ligand can have different substituant) and mixtures thereof; or their niobium counterparts.d) a lanthanide metal source (Sc, Y, La, Ce, Pr, Nd, Gd . . . ) source with at least one β-diketonate ligand, such as of the form Ln(—O—C(R¹)—C(R²)—C(R³)—O—)(—O—C(R⁴)—C(R⁵)—C(R⁶)—O—)(—O—C(R⁷)—C(R⁸)—C(R⁹)—O—) where each Rⁱ is independently H or a C1-C6 carbon chain, either linear, branched or cyclic), or of the form of a cyclopentadienyl lanthanide Ln(R¹Cp)(R²Cp)(R³CP) (where each Rⁱ is independently H or a C1-C6 carbon chain, either linear, branched or cyclic), Ln(NR¹R²)(NR³R⁴)(NR⁵R⁶) (where each Rⁱ is bonded to nitrogen and is independently H or a C1-C6 carbon chain, either linear, branched or cyclic or an alkylsilyl chain of the form SiR⁷R⁸R⁹ where each Rⁱ is bonded to silicon and is independently H or a C1-C4 carbon chain, either linear, branched or cyclic)e) a IVA metal source with M² is similar or different from M¹ but in which the M² source is different from the M¹ metal source introduced in step b) in the reactor, said IVA metal source being selected from (R_yOp)_x(R_tCp)_zM¹R′_4-x-z, M¹(OR¹)₄ or other alkoxide-containing metal sources, M(NR¹R²)₄, or adducts containing these species.f) a divalent metal (preferably Mg, Ca, Zn) selected from the group comprising metal β-diketonates or adducts containing these species.

The invention is directed to the deposition of dielectric films (formula (M¹_1-a M²_a) O_b N_c) onto a support such as a wafer, in a reactor using ALD, CVD, MOCVD, pulse CVD processes.

Example IV

Deposition of M¹M² Metal Oxynitride Films with M¹ being Preferably Hf or Zr and M² being Preferably Si or Al

The film deposited on the substrate in this example illustrates the case wherein a≠0, b≠0 and c≠0.

All the information given in Example III is applicable in this case, except that nitrogen needs to be introduced into the reactor.

The nitrogen source shall be selected from the group comprising nitrogen (N2), ammonia, hydrazine and alkyl derivatives, N-containing radicals (for instance N., NH., NH₂.), NO, N₂O, NO₂.

Example V

Examples of New Group IV Precursors for Group IV Metal Containing Thin Film Deposition

Hf(iPrCp)₂H₂, Hf(nPrCp)₂H₂, Hf(EtCp)₂H₂, Hf(MeCp)₂Me₂, Hf(EtCp)₂Me₂, Hf(MeCp)₂EtMe, Hf(EtCp)₂EtMe, Hf(MeCp)₂nPrMe, Hf(MeCp)₂Et₂, Hf(MeCp)(EtCp)Me₂, Hf(MeCp)(EtCp)EtMe, Hf(iPrCp)₂EtMe, Hf(Me₂Cp)₂Me₂, Hf(Et₂Cp)₂Me₂, Hf(MeCp)(MeOp)Me₂, Hf(EtCp)(MeOp)Me₂, Hf(MeCp)(EtOp)Me₂, Hf(MeCp)(MeOp)EtMe, Hf(iPrOp)₂H₂, Hf(nPrOp)₂H₂, Hf(EtOp)₂H₂, Hf(MeOp)₂Me₂, Hf(EtOp)₂Me₂, Hf(MeOp)₂EtMe, Hf(EtOp)₂EtMe, Hf(MeOp)₂nPrMe, Hf(MeOp)₂Et₂, Hf(MeOp)(EtOp)Me₂, Hf(MeOp)(EtOp)EtMe, Hf(iPrOp)₂EtMe, Hf(Me₂Op)₂Me₂, Hf(Et₂Op)₂Me₂, Hf(C₅Me₅)₂Me₂, Hf(MeCp)₂Cl₂, Hf(EtCp)₂Cl₂, Hf(iPrCp)₂Cl₂, Hf(MeCp)(EtCp)Cl₂, HfCp(MeCp)Cl₂, Hf(MeOp)₂Cl₂, Hf(EtOp)₂Cl₂, Hf(iPrOp)₂Cl₂, Hf(MeOp)(EtOp)Cl₂, HfOp(MeOp)Cl₂, Zr(iPrCp)₂H₂, Zr(nPrCp)₂H₂, Zr(EtCp)₂H₂, Zr(MeCp)₂Me₂, Zr(EtCp)₂Me₂, Zr(MeCp)₂EtMe, Zr(EtCp)₂EtMe, Zr(MeCp)₂nPrMe, Zr(MeCp)₂Et₂, Zr(MeCp)(EtCp)Me₂, Zr(MeCp)(EtCp)EtMe, Zr(iPrCp)₂EtMe, Zr(Me₂Cp)₂Me₂, Zr(Et₂Cp)₂Me₂, Zr(MeCp)(MeOp)Me₂, Zr(EtCp)(MeOp)Me₂, Zr(MeCp)(EtOp)Me₂, Zr(MeCp)(MeOp)EtMe, Zr(iPrOp)₂H₂, Zr(nPrOp)₂H₂, Zr(EtOp)₂H₂, Zr(MeOp)₂Me₂, Zr(EtOp)₂Me₂, Zr(MeOp)₂EtMe, Zr(EtOp)₂EtMe, Zr(MeOp)₂nPrMe, Zr(MeOp)₂Et₂, Zr(MeOp)(EtOp)Me₂, Zr(MeOp)(EtOp)EtMe, Zr(iPrOp)₂EtMe, Zr(Me₂Op)₂Me₂, Zr(Et₂Op)₂Me₂, Zr(C₅Me₅)₂Me₂, Zr(MeCp)₂Cl₂, Zr(EtCp)₂Cl₂, Zr(iPrCp)₂Cl₂, Zr(MeCp)(EtCp)Cl₂, ZrCp(MeCp)Cl₂, Zr(MeOp)₂Cl₂, Zr(EtOp)₂Cl₂, Zr(iPrOp)₂Cl₂, Zr(MeOp)(EtOp)Cl₂, ZrOp(MeOp)Cl₂, Ti(iPrCp)₂H₂, Ti(nPrCp)₂H₂, Ti(EtCp)₂H₂, Ti(MeCp)₂Me₂, Ti(EtCp)₂Me₂, Ti(MeCp)₂EtMe, Ti(EtCp)₂EtMe, Ti(MeCp)₂nPrMe, Ti(MeCp)₂Et₂, Ti(MeCp)(EtCp)Me₂, Ti(MeCp)(EtCp)EtMe, Ti(iPrCp)₂EtMe, Ti(Me₂Cp)₂Me₂, Ti(Et₂Cp)₂Me₂, Ti(MeCp)(MeOp)Me₂, Ti(EtCp)(MeOp)Me₂, Ti(MeCp)(EtOp)Me₂, Ti(MeCp)(MeOp)EtMe, Ti(iPrOp)₂H₂, Ti(nPrOp)₂H₂, Ti(EtOp)₂H₂, Ti(MeOp)₂Me₂, Ti(EtOp)₂Me₂, Ti(MeOp)₂EtMe, Ti(EtOp)₂EtMe, Ti(MeOp)₂nPrMe, Ti(MeOp)₂Et₂, Ti(MeOp)(EtOp)Me₂, Ti(MeOp)(EtOp)EtMe, Ti(iPrOp)₂EtMe, Ti(Me₂Op)₂Me₂, Ti(Et₂Op)₂Me₂, Ti(C₅Me₅)₂Me₂, Ti(MeCp)₂Cl₂, Ti(EtCp)₂Cl₂, Ti(iPrCp)₂Cl₂, Ti(MeCp)(EtCp)Cl₂, TiCp(MeCp)Cl₂, Ti(MeOp)₂Cl₂, Ti(EtOp)₂Cl₂, Ti(iPrOp)₂Cl₂, Ti(MeOp)(EtOp)Cl₂, TiOp(MeOp)Cl₂,

It will be understood that many additional changes in the details, materials, steps and arrangement of parts, which have been herein described in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims. Thus, the present invention is not intended to be limited to the specific embodiments in the examples given above.

Claims

1. A method of forming on at least one substrate at least one metal containing dielectric film having the formula (M11-a M2a) Ob Nc, wherein: 0≦a<10<b≦3,0≦c≦1,M1 being a metal and M2 being selected from the group consisting of Mg, Ca, Zn, B, Al, In, Lanthanides, Si, Ge, Sn, Ti, Zr, Hf, V, Nb, and Ta;

2. The method of claim 1, wherein the oxygen containing fluid is selected from the group consisting of O2, O3, H2O, H2O2, oxygen-containing radicals, and mixtures thereof.

3. The method of claim 1, wherein the nitrogen-containing fluid is selected from the group consisting of N2, NH3, hydrazine and its alkyl or aryl derivatives, nitrogen-containing radicals, and mixtures thereof.

4. The method of claim 1, wherein the oxygen and nitrogen-containing fluid is selected from the group consisting of NO, NO2, N2O, N2O5, N2O4 and mixtures thereof.

5. The method of claim 1, wherein the pressure is comprised between 1 Pa and 100 000 Pa.

6. The method of claim 1, wherein the metal containing precursor, the M2 containing precursor and the oxygen containing and/or nitrogen containing fluid are introduced simultaneously into the reactor.

7. The method of claim 1, further comprising the step of providing at least one metal containing precursor containing at least one of the following precursors: M1(NMe2)4, M1(NEt2)4, M1(NMeEt)4, M1(mmP)4, M1(OtBu)4, M1(OtBu)2(mmp)2 and mixtures thereof.

8. The method of claim 7, further comprising the steps of mixing together at least two different metal containing precursors A and B to provide a precursor mixture, A being selected from the group consisting of Hf(MeCp)2Me2, HfCp(MeCp)Cl2, Hf(MeCp)2Cl2, HfCp(MeCp)Me2, Hf(EtCp)(MeCp)Me2, Hf(MeCp)2(CO)2, Zr(MeCp)2Cl2, ZrCp(MeCp)Me2, Zr(EtCp)(MeCp)Me2, Zr(EtCp)2Me2, Zr(MeCp)2(CO)2 and mixtures thereof and B being selected from the group consisting of M1(NMe2)4, M1(NEt2)4, M1(NMeEt)4, M1(mmp)4, M1(OtBu)4, M1(OtBu)2(mmp)2 and mixtures thereof; and providing said metal precursor mixture into said reactor.

9. The method of claim 1, wherein the at least one metal containing precursor introduced in step b) has a melting point below 50° C.

10. The method of claim 9, wherein the at least one metal containing precursor is liquid at room temperature.

11. The method of claim 1, to form an M1oxide containing film wherein a=0, b being equal to about 2 and c=0.

12. The method of claim 1, to form an M1oxynitride-containing dielectric film wherein a=0, 1.5≦b≦2.5 and 0<c≦0.5.

13. The method of claim 1, to form an M1M2 oxide containing dielectric film wherein 0≦a<1 and c=0, the M2 containing precursor of step (c) being introduced into the reactor, said precursor being selected from the group consisting of Si, Mg and Ta.

14. The method of claim 13, wherein the M2 containing precursor is selected from the group consisting of disiloxane, trisilylamine, disilane, trisilane, an alkoxysilane having the formula SiHx(OR1)4-x, a silanol having the formula_Si(OH)x(OR1)4-x, an aminosilane having the formula SiHx(NR1R2)4-x, Ta(OMe)5, Ta(OEt)5, Ta(OR1)4(O—C(R2)(R3)—CH2—OR4), Ta(OR1)4(O—C(R2)(R3)—CH2—N(R4)(R5)), Ta(NMe2)5, Ta(NEt2)4, Ta(NEt2)5, Ta(═NR1)(NR2R3)3, an alkylsilyl chain of the form SiR7R8R9 where each Ri is bonded to silicon, a IVA metal source wherein the M2 source is different from the M1 metal source introduced in step b) in the reactor, said IVA metal source being selected from the group consisting of M1(OR1)4, M(NR1R2)4, and adducts containing these species, a divalent metal A source having the formula A(—O—C(R1)—C(R2)—C(R3)—O—)(—O—C(R4)—C(R5)—C(R6)—O—), and a cyclopentadienyl divalent metal A source having the formula A(R1Cp)(R2Cp), wherein each Ri is independently selected from the group consisting of H and a C1-C6 carbon chain.

15. The method of claim 1, to form an M1M2 oxynitride containing dielectric film wherein 0≦a<1 and 0<c≦0.5, the M2 containing precursor of step (c) being introduced into the reactor, said precursor being selected from the group consisting of Si, Mg and Ta, and wherein in step (d) at least one oxygen containing precursor and at least one nitrogen containing precursor is introduced into the reactor.

16. The method of claim 15, wherein the M2 containing precursor is selected from the group consisting of disiloxane, trisilylamine, disilane, trisilane, an alkoxysilane having the formula SiHx(OR1)4-x, a silanol having the formula_Si(OH)x(OR1)4-x, an aminosilane having the formula SiHx(NR1R2)4-x, Ta(OMe)5, Ta(OEt)5, Ta(OR1)4(O—C(R2)(R3)—CH2—OR4), Ta(OR1)4(O—C(R2)(R3)—CH2—N(R4)(R5)), Ta(NMe2)5, Ta(NEt2)4, Ta(NEt2)5, Ta(═NR1)(NR2R3)3, an alkylsilyl chain of the form SiR7R8R9 where each Ri is bonded to silicon, a IVA metal source wherein the M2 source is different from the M1 metal source introduced in step b) in the reactor, said IVA metal source being selected from the group consisting of M1(OR1)4, M(NR1R2)4, and adducts containing these species, a divalent metal A source having the formula A(—O—C(R1)—C(R2)—C(R3)—O—)(—O—C(R4)—C(R5)—C(R6)—O—), and a cyclopentadienyl divalent metal A source having the formula A(R1Cp)(R2Cp), wherein each R1 and R2 is independently selected from the group consisting of H and a C1-C6 carbon chain.