Patent Application
20080286464
The semiconductor fabrication industry has an interest in depositing barium strontium titanate films (“BST”) for constructing various electronic devices in integrated circuits. The industry has sought precursors of barium strontium and titanium that are stable, liquid and readily decompose under standard deposition conditions leaving high purity BST films and removing in the vapor phase the remainder of the precursors of barium, strontium and titanium, typically in the form of ligands that reversibly bind the metals until the deposition conditions are provide wherein the metal is deposited from the ligand precursor resulting in essentially deposited metal and volatile, gas phase leaving groups constituting the ligand that bound the metal in the precursor form or decomposition components of the ligand which still exhibit the properties of being good leaving groups that do not contaminate the deposited BST film and typically leave as volatile, gaseous groups.
Representative art to this field includes:
The present invention is directed to a metal containing complex represented by the structures selected from the group consisting of:
wherein M is selected from Mg, Ca, Sr, and Ba; R1 and R3 are independently selected from the group consisting of linear or branched alkyl, alkoxyalkyl, fluoroalkyl: having from 1 to 10 carbon atoms, cycloaliphatic, and aryl having from 4 to 12 carbon atoms; R2 is selected from the group consisting of hydrogen, linear or branched alkyl, fluoroalkyl, alkoxy: having from 1 to 10 carbon atoms, cycloaliphatic, and aryl: having from 4 to 12 carbon atoms; L1 is selected from the group consisting of the organic amide class RCONR′R″ wherein R and R′ are linear or branched alkyl having from 1-10 carbon atoms and they can be connected to form a cyclic group (CH2)q, wherein q is from 4-6, and R″ is selected from alkyl having from 1 to 4 carbon atoms and cycloalkyl having from 4 to 8 carbon atoms; L2 is selected from the group consisting of H2O and ROH wherein R is linear or branched alkyl having from 1-10 carbon atoms and they can be connected to form a cyclic group (CH2)q, wherein q is from 4-6; n is a number selected from between 1 and 4; m is selected from a number between 0 to 4, p is selected from 1, 2;
wherein M is selected from Mg, Ca, Sr, and Ba; R1 and R4 are selected from the group consisting of linear or branched alkyl, alkoxyalkyl, fluoroalkyl: having from 1 to 10 carbon atoms, cycloaliphatic, and aryl: having from 4 to 12 carbon atoms; R2 and R3 are selected from the group consisting of hydrogen, linear or branched alkyl, alkoxyalkyl, fluoroalkyl, alkoxy: having from 1 to 10 carbon atoms, cycloaliphatic, and aryl: having from 4 to 12 carbon atoms, L is selected from the group of the organic amide class RCONR′R″ wherein R and R′ are independently alkyl having from 1-10 carbon atoms and they can be connected to form a cyclic group (CH2)q, wherein q is from 4-6, and R″ is selected from alkyl having from 1 to 4 carbon atoms and cycloalkyl having from 4 to 8 carbon atoms; n is a number selected from between 0 and 4; m is selected from a number between 1 to 4; p is selected from 1, 2; μ-L indicates L is connected to two metals, M, via μL's oxygen atom when p=2; and,
wherein M is selected from Mg, Ca, Sr, and Ba; R1 and R3 are independently selected from the group consisting of linear or branched alkyl, alkoxyalkyl, fluoroalkyl: from 1 to 10 carbon atoms, cycloaliphatic, and aryl: having from 4 to 12 carbon atoms; R2 is selected from the group consisting of hydrogen, linear or branched alkyl, fluoroalkyl, alkoxy: from 1 to 10 carbon atoms, cycloaliphatic, and aryl: having from 4 to 12 carbon atoms; L is selected from the group of the organic amide class RCONR′R″ wherein R and R′ are independently linear or branched alkyl having from 1-10 carbon atoms and they can be connected to form a cyclic group (CH2)q, wherein q is from 4-6, and R″ is selected from alkyl having from 1 to 4 carbon atoms and cycloalkyl: having from 4 to 8 carbon atoms, n is a number selected from between 0 and 4; m is selected from a number between 1 to 4; p is selected from 1, 2; μ-L indicates L is connected to two metals, M, via μL's oxygen atom when p=2.
Novel Sr and Ba complexes containing both beta-diketonates and N-methyl-pyrrolidone have been synthesized and characterized. Thermogravimetric Analysis (TGA) experiments indicate these complexes are volatile, and that they can be employed as potential precursors for chemical vapor deposition (CVD), cyclic chemical vapor deposition (CCVD), or atomic layer deposition (ALD) of strontium titanate (STO) or barium strontium titanate films (BST) films in semiconductor fabrication. In the deposition of STO and BST films, the titanium source is selected from titanium containing precursors exemplified by titanium alkoxides or beta-diketonates such as Ti(OPri)4, Ti(tmhd)2(OPri)2, where Pri=isopropyl, where tmhd=2,2,6,6-tetramethyl-3,5-heptanedionate, Ti(mpd)(tmhd)2, where mpd=2-methyl-2,4-pentanedioxy, Ti(4-(2-methylethoxy)imino-2-pentanoate)2, and analogous titanium ligands and derivatives.
These Group 2 metal complexes are precursors capable of depositing Group 2 metal-containing films for semiconductor applications. The metal complexes include:
(i) Group 2 beta-diketonate with organic amides as adducts with a formula of [M(R1C(O)CR2C(O)R3)2(L1)n(L2)m]p wherein R1 and R3 are independently selected from the group consisting of linear or branched alkyl, alkoxyalkyl, fluoroalkyl: having from 1 to 10 carbon atoms, cycloaliphatic, and aryl: having from 4 to 12 carbon atoms; R2 is selected from the group consisting of hydrogen, linear or branched alkyl, fluoroalkyl, alkoxy: having from 1 to 10 carbon atoms, cycloaliphatic, and aryl: having from 4 to 12 carbon atoms; L, is selected from the group consisting of the organic amide class RCONR′R″ wherein R and R′ are linear or branched alkyl having from 1-10 carbon atoms and they can be connected to form a cyclic group (CH2)q, wherein q is from 4-6, and R″ is selected from alkyl having from 1 to 4 carbon atoms and cycloalkyl having from 4 to 8 carbon atoms; L2 is selected from the group consisting of the H2O and ROH wherein R is linear or branched alkyl having from 1-10 carbon atoms and they can be connected to form a cyclic group (CH2)q, wherein q is from 4-6; n is a number selected from between 1 and 4; m is selected from a number between 0 to 4; p is selected from 1, 2; and,
(ii) Group 2 beta-ketoiminate with organic amides as adducts with a formula of [M(R1C(O)CR2C(NR3)R4)2(μ-L)nLm]p wherein R1 and R4 are independently selected from the group consisting of alkyl, alkoxyalkyl, fluoroalkyl: having from 1 to 10 carbon atoms, cycloaliphatic, and aryl: having from 4 to 12 carbon atoms; R2 and R3 are independently selected from the group consisting of hydrogen, alkyl, alkoxyalkyl, fluoroalkyl, alkoxy: having from 1 to 10 carbon atoms, cycloaliphatic, and aryl: having from 4 to 12 carbon atoms; L is selected from the group of the organic amide class of the form RCONR′R″ wherein R and R′ are independently alkyl having from 1-10 carbon atoms and they can be connected to form a cyclic group (CH2)q, wherein q is from 4-6, preferably 5, and R″ is selected from alkyl having from 1 to 4 carbon atoms and cycloalkyl having from 4 to 8 carbon atoms; n is a number selected from between 1 and 10, preferably 3, 4; m is selected from a number between 0 to 4; and p is selected from 1, 2; p-L indicates L is connected to two metals, M, via μL's oxygen atom when p=2.
(iii) Group 2 amidinates with organic amides as adducts with a formula of [M(R1NC(R2)NR3)2(μ-L)nLm]p wherein R1 and R3 are independently selected from the group consisting of linear or branched alkyl, alkoxyalkyl, fluoroalkyl: from 1 to 10 carbon atoms, cycloaliphatic, and aryl: having from 4 to 12 carbon atoms; R2 is selected from the group consisting of hydrogen, linear or branched alkyl, fluoroalkyl, alkoxy: from 1 to 10 carbon atoms, cycloaliphatic, and aryl: having from 4 to 12 carbon atoms; L either bridging between two metal atoms or coordinating to one metal atom is selected from the group of the organic amide class RCONR′R″ wherein R and R′ are independently linear or branched alkyl having from 1-10 carbon atoms and they can be connected to form a cyclic group (CH2)q, wherein q is from 4-6, and R″ is selected from alkyl having from 1 to 4 carbon atoms and cycloalkyl: having from 4 to 8 carbon atoms, n is a number selected from between 0 and 4; m is selected from a number between 1 to 4; and p is selected from 1, 2; μ-L indicates L is connected to two metals, M, via μL's oxygen atom when p=2.
This invention is related to Group 2 metal-containing complexes having both beta-ketonate or beta-ketoiminate or amidinate and organic amides and their solutions, which are useful for fabricating conformal metal containing films on substrates such as silicon, metal nitride, metal oxide and other metal layers via deposition processes, e.g., chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), low pressure chemical vapor deposition (LPCVD), plasma enhanced atomic layer deposition (PE ALD) and atomic layer deposition (ALD). Such conformal metal containing films have applications ranging from computer chips, optical device, magnetic information storage, to metallic catalyst coated on a supporting material. In contrast to prior polydentate beta-ketoiminate precursors, the polydentate beta-ketoiminate ligands incorporate at least one amino organo imino functionality, which is in contrast to the literatures reported alkoxy group as the donating ligand.
One type of structure in the metal precursor is illustrated in structure A below where the metal M is a Group 2 metal having the formula:
wherein M is selected from Mg, Ca, Sr, and Ba; R1 and R3 are independently selected from the group consisting of linear or branched alkyl, alkoxyalkyl, fluoroalkyl: having from 1 to 10 carbon atoms, cycloaliphatic, and aryl having from 4 to 12 carbon atoms; R2 is selected from the group consisting of hydrogen, linear or branched alkyl, fluoroalkyl, alkoxy: having from 1 to 10 carbon atoms, cycloaliphatic, and aryl: having from 4 to 12 carbon atoms; L1 is selected from the group consisting of the organic amide class RCONR′R″ wherein R and R′ are linear or branched alkyl having from 1-10 carbon atoms and they can be connected to form a cyclic group (CH2)q, wherein q is from 4-6, and R″ is selected from alkyl having from 1 to 4 carbon atoms and cycloalkyl having from 4 to 8 carbon atoms; L2 is selected from the group consisting of the organic amide class RCONR′R″ wherein R and R′ are independently linear or branched alkyl having from 1-10 carbon atoms and they can be connected to form a cyclic group (CH2)q, wherein q is from 4-6 and neutral oxygen; n is a number selected from between 1 and 4; m is selected from a number between 0 to 4; p is selected from 1, 2.
Another type of structure in the metal precursor is illustrated in structure B below where the metal M is a Group 2 metal having the formula:
wherein M is selected from Mg, Ca, Sr, and Ba; R1 and R4 are selected from the group consisting of linear or branched alkyl, alkoxyalkyl, fluoroalkyl: having from 1 to 10 carbon atoms, cycloaliphatic, and aryl: having from 4 to 12 carbon atoms; R2 and R3 are selected from the group consisting of hydrogen, linear or branched alkyl, alkoxyalkyl, fluoroalkyl, alkoxy: having from 1 to 10 carbon atoms, cycloaliphatic, and aryl: having from 4 to 12 carbon atoms, L is selected from the group of the organic amide class RCONR′R″ wherein R and R′ are independently alkyl having from 1-10 carbon atoms and they can be connected to form a cyclic group (CH2)q, wherein q is from 4-6, and R″ is selected from alkyl having from 1 to 4 carbon atoms and cycloalkyl having from 4 to 8 carbon atoms; n is a number selected from between 0 and 4; m is selected from a number between 1 to 4; p is selected from 1, 2; μ-L indicates L is connected to two metals, M, via μL's oxygen atom when p=2.
The third type of structure in the metal precursor is illustrated in structure C below where the metal M is a Group 2 metal having the formula:
wherein M is selected from Mg, Ca, Sr, and Ba; R1 and R3 are independently selected from the group consisting of linear or branched alkyl, alkoxyalkyl, fluoroalkyl: from 1 to 10 carbon atoms, cycloaliphatic, and aryl: having from 4 to 12 carbon atoms; R2 is selected from the group consisting of hydrogen, linear or branched alkyl, fluoroalkyl, alkoxy: from 1 to 10 carbon atoms, cycloaliphatic, and aryl: having from 4 to 12 carbon atoms; L is selected from the group of the organic amide class RCONR′R″ wherein R and R′ are independently linear or branched alkyl having from 1-10 carbon atoms and they can be connected to form a cyclic group (CH2)q, wherein q is from 4-6, and R″ is selected from alkyl having from 1 to 4 carbon atoms and cycloalkyl: having from 4 to 8 carbon atoms; n is a number selected from between 0 and 4; m is selected from a number between 1 to 4; p is selected from 1, 2; μ-L indicates L is connected to two metals, M, via μL's oxygen atom when p=2.
These metal-containing complexes having both beta-ketonate or beta-ketoiminate ligands and organic amides can be employed as potential precursors to make thin metal or metal oxide films via either the chemical vapor deposition (CVD) or atomic layer deposition (ALD) method at temperatures less than 500° C. The CVD process can be carried out with or without reducing or oxidizing agents, whereas an ALD process usually involves the employment of another reactant, such as a reducing agent or oxidizing agent.
For multi-component metal oxides such as STO and BST, these metal-containing complexes, having beta-ketonate or beta-ketoiminate or amidinate ligands and organic amides, can be delivered in vapor phase into a CVD or ALD reactor via well-known bubbling or vapor draw techniques as strontium or barium sources. The titanium source is selected from titanium alkoxides or beta-diketonates such as Ti(OPri)4, Ti(tmhd)2(OPri)2, where Pri=isopropyl, where tmhd=2,2,6,6-tetramethyl-3,5-heptanedionate, Ti(mpd)(tmhd)2, where mpd=2-methyl-2,4-pentanedioxy, Ti(4-(2-methylethoxy)imino-2-pentanoate)2, and analogous titanium ligands and derivatives. A direct liquid delivery method can also be employed by dissolving the titanium, strontium as well as barium complexes in a suitable solvent or a solvent mixture to prepare a solution with a molar concentration from 0.001 to 2 M, depending the solvent or mixed-solvents employed. Oxidizing agents for the deposition process include oxygen, water, hydrogen peroxide, oxygen plasma, nitrous oxide, and ozone. In a preferred embodiment, the multi-compoent metal oxide films are grown in the temperature range of 200 to 500° C., preferably 250 to 350° C. whereby an amorphous STO or BST films are obtained. A thermal annealing is needed to convert the resulting films from amorphous into crystalline form. The annealing can be conducted at a higher temperature 500 to 1200° C. under oxidizing conditions, preferably in the range of 500 to 700° C. for high k dielectrics in DRAM applications. The thickness of the STO or BST film is in the range of 1 nm to 500 nm, preferably 2 nm to 10 nm, deposited on compatible substrates including platinum(Pt), RuO2, SrRuO3, silica, silicon nitride, and silicon. The process chamber pressure may preferably be from about 0.1 Torr to 100 Torr, and more preferably from about 0.1 Torr to 5 Torr.
The solvent employed in solubilizing the precursor for use in a deposition process may comprise any compatible solvent or their mixture, including: aliphatic hydrocarbons, aromatic hydrocarbons, ethers, esters, nitrites, and alcohols. The solvent component of the solution preferably comprises a solvent selected from the group consisting of: glyme solvents having from 1 to 20 ethoxy —(C2H4O)— repeat units; C2-C12 alkanols, organic ethers selected from the group consisting of dialkyl ethers comprising C1-C6 alkyl moieties, C4-C8 cyclic ethers; C12-C60 crown O4-O20 ethers (wherein C is the number of carbon atoms in the ether compound and O is the number of oxygen atoms in the ether compound); C6-C12 aliphatic hydrocarbons; C6-C18 aromatic hydrocarbons; organic esters; organic amines, polyamines and organic amides.
Another class of solvents that offers advantages is the organic amide class of the form RCONR′R″, wherein R and R′ are independently linear or branched alkyl having from 1-10 carbon atoms, and they can be connected to form a cyclic group (CH2)q, wherein q is from 4-6, preferably 5, and R″ is selected from alkyl having from 1 to 4 carbon atoms and cycloalkyl having 4 to 8 carbon atoms. N-methylpyrrolidinone (NMP), N,N-Diethylformamide (DEF), N,N-Diethylacetamide (DEAC), N,N-Dimethylacetamide (DMAC), and N-cyclohexyl 2-pyrrolidinone are examples.
The following examples illustrate the preparation of the metal-containing complexes with beta-diketone or beta-ketoiminate ligands as well as their use as precursors in metal-containing film deposition processes.
0.52 g (3.80 mmol) of BaH2 was loaded in flask with 15 mL of toluene. To this flask was added 2.15 g (21.70 mmol) NMP followed by addition of 1.57 g (7.60 mmol) 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (“hfac”). Stirred reaction mixture at room temperature until bubbling ceased after 5-10 minutes. Removed volatiles under vacuum and noticed the formation of a white solid. Upon completion of evaporation, a liquid was left which was taken up in hexane and recrystallized in −40° C. freezer. Decanted out hexanes from recrystallized solid and solid taken up in toluene and recrystallized again in freezer. Decanted toluene from crystals. Crystals identified by crystal structure analysis as the dimer Ba2(hfac)4(NMP)5.
0.50 g (5.58 mmol) of SrH2 was loaded into a 100 mL Schlenk flask with 5 g of NMP. To this flask was added 2.06 g (11.16 mmol) 2,2,6,6-tetramethyl-3,5-heptanedione (“tmhd”) in 5 g of NMP and bubbling occurred. Left to stir over night at room temperature. Reaction mixture was subjected to vacuum transferred at 65-70° C. leaving behind a grey solid weighing 2.86 g. Recrystallized in a 1:1 solution of hexane to pentane in −40° C. freezer to afford clear needle like crystals that were identified by crystal structure analysis as the dimer Sr2(tmhd)4(NMP)4.
To a suspension of 0.50 g (5.58 mmol) SrH2 in hexanes was added 20.10 g (11.16 mmol) 2,2,6,6-tetramethyl-3,5-heptanedione (“tmhd”) and 2.60 g (22.32 mmol) N,N-diethylacetamide (DEAC) in hexanes at room temperature. Bubbling and heat were given off and the suspension turned to solution after approximately 10 minutes. The reactin mixture was stirred for 16 hours and removal of hexanes to afford an oil that was set up for vacuum transfer and heated at 80° C. under 300 mTorr for several hours. 2.38 g of clear residual slurry (68% yield) was collected and recrystallization in pentane an −40° C. gave rise to clear crystals. The crystals were identified by crystal structure analysis as Sr2(tmhd)4(DEAC)3
0.50 g (3.59 mmol) of BaH2 was loaded into a 100 mL Schlenk flask with 15 mL of hexane. To this flask was added a solution of 1.32 g (7.18 mmol) tmhd and 1.42 (14.35 mmol) NMP in 5 mL hexane and bubbling was witnessed. After approximately 6 hours, the hexane was evaporated under vacuum leaving behind a grey solid weighing 2.32 g. Recrystallized in octane giving clear hexagonal-like crystals that were sent for crystal structure analysis and confirmed as the proposed dimer. A 90% yield was obtained based off of crude.
To a solution of 15.00 g (105.49 mmol) 2,2-dimethyl-3,5-hexanedione in 50 mL of toluene loaded with 30.00 g sodium sulfate was added 12.47 g (210.97 mmol) isopropylamine. The mixture was refluxed for 4 days. Removal of toluene resulted in a yellow oil, which was subjected to vacuum transfer at 80° C. under 125 mTorr. 16.5 g of clear oil was obtained with a yield of 84%. 1H NMR (500 MHz, C6D6): δ=11.50 (s, 1H), 5.16 (s, 1H), 3.11 (m, 1H), 1.49 (s, 3H), 1.31 (s, 9H), 0.79 (d, 6H).
To a solution of 5.00 g (35.16 mmol) 2,2-dimethyl-3,5-hexanedione in 20 mL of toluene loaded with 10.00 g of sodium sulfate was added 5.14 g (70.32 mmol) sec-butylamine. The mixture was refluxed 3 days. 4.90 g of light yellow oil was obtained after work-up. The isolated yield was 71%. 1H NMR (500 MHz, C6D6): δ=11.52 (s, 1H), 5.18 (s, 1H), 2.95 (m, 1H), 1.51 (s, 3H), 1.31 (s, 9H), 1.14 (s, 2H), 0.80 (d, 3H), 0.67 (t, 3H).
To a suspension of 1 g (1.66 mmol) Ba(N(SiMe3)2)2(THF)2 in hexane was added 0.61 g (3.32 mmol) of 2,2-dimethyl-5-(iso-propylamino)-3-hexanone and 0.66 g (6.64 mmol) of NMP in hexane at room temperature. The reaction mixture turned to solution after approximately 30 minutes. After tirring for 16 hours, hexane was evaporated under vacuum to provide 0.95 g of a white solid. The white solid was heated in hexane, filtered, and recrystallized an −40° C. to give rise to foggy-white crystals. 1H NMR (500 MHz, C6D6): δ=5.06 (s, 1H), 3.75 (m, 1H), 2.42 (s, 3H), 2.40 (t, 2H), 1.98 (t, 2H), 1.83 (s, 3H), 1.44 (s, 9H), 1.34 (d, 6H), 1.17 (m, 2H).
To a solution of 1 g (1.81 mmol) of Sr(N(SiMe3)2)2(THF)2 in hexanes was added 0.66 g (3.62 mmol) of 2,2-dimethyl-5-(sec-butylamino)-3-hexanone and 0.72 g (7.24 mmol) of NMP in hexanes at room temperature. After stirring for 16 hours, hexanes were evaporated under vacuum. Recrystallization in hexanes at −20° C. resulted in a opaque white solid. 1H NMR (500 MHz, C6D6): δ=5.06 (s, 1H), 3.75 (m, 1H), 2.46 (s, 3H), 2.42 (t, 2H), 2.07 (t, 2H), 1.90 (s, 3H), 1.47 (s, 9H), 1.47 (d, 6H), 1.21 (m, 2H).
To a solution of 1 g (1.81 mmol) Sr(N(SiMe3)2)2(THF)2 in 10 mL hexanes at room temperature was added 0.71 g (3.62 mmol) of 2,2-dimethyl-5-(sec-butylamino)-3-hexanone and 0.83 g (7.24 mmol) DEAC in 10 mL hexanes. Reaction was stirring for 16 hours. Evaporation of hexanes afforded a wet off-white solid. 1H NMR (500 MHz, C6D6): δ=5.05 (s, 1H), 3.59 (m, 1H), 3.17 (q, 2H), 2.51 (q, 2H), 1.96 (s, 3H), 1.79 (s, 3H), 1.55 (s, 9H) 1.44 (m, 2H), 1.44 (d, 3H), 1.03 (t, 3H) 0.96 (t, 3H), 0.56 (t, 3H).
This patent application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/938,233 filed 16 May 2007.
| Number | Date | Country | |
|---|---|---|---|
| 60938233 | May 2007 | US |
