Scalable lead zirconium titanate (pzt) thin film material and deposition method, and ferroelectric memory device structures comprising such thin film material

Abstract

A novel lead zirconium titanate (PZT) material having unique properties and application for PZT thin film capacitors and ferroelectric capacitor structures, e.g., FeRAMs, employing such thin film material. The PZT material is scalable, being dimensionally scalable, pulse length scalable and/or E-field scalable in character, and is useful for ferroelectric capacitors over a wide range of thicknesses, e.g., from about 20 nanometers to about 150 nanometers, and a range of lateral dimensions extending to as low as 0.15 μm. Corresponding capacitor areas (i.e., lateral scaling) in a preferred embodiment are in the range of from about 10 4 to about 10 −2 μm 2 . The scalable PZT material of the invention may be formed by liquid delivery MOCVD, without PZT film modification techniques such as acceptor doping or use of film modifiers (e.g., Nb, Ta, La, Sr, Ca and the like).

What is claimed is: 
     
         1 . A precursor composition for forming a PZT film on a substrate by liquid delivery MOCVD, said precursor composition comprising lead, zirconium and titanium precursors each in a solvent medium so that the precursors when vaporized form precursor vapor which when contacted with the substrate forms a film characterized by at least one of the characteristics of:
 (i) said film having an A/B ratio of from 0.612 to 1.53, wherein the A/B ratio is Pb to (Zr+Ti); and   (ii) said film being at least one of dimensional scalable, pulse length scalable and E-field scalable.   
     
     
         2 . The precursor composition of  claim 1 , wherein the lead precursor is selected from the group consisting of Pb(thd) 2  and Pb(thd) 2 pmdeta. 
     
     
         3 . The precursor composition of  claim 1 , wherein the zirconium precursor is selected from the group consisting of Zr(thd) 4  and Zr(O-i-Pr) 2 (thd) 2 . 
     
     
         4 . The precursor composition of  claim 1 , wherein the titanium precursor is Ti(O-i-Pr) 2 (thd) 2 . 
     
     
         5 . The precursor composition of  claim 1 , wherein the lead, zirconium and titanium precursors are selected from the group consisting of:
 lead bis(2,2,6,6-tetramethyl-3,5-heptanedionate);   lead bis(2,2,6,6-tetramethyl-3,5-heptanedionate) N,N′,N″-pentamethyl diethylenetriamine;   zirconium tetrakis(2,2,6,6-tetramethyl-3,5-heptanedionate);   zirconium bis(isopropoxide)bis(2,2,6,6-tetramethyl-3,5-heptanedionate);   Zr 2 (O-i-Pr) 6 (2,2,6,6-tetramethyl-3,5-heptanedionate) 2 ; and   Ti(O-i-Pr) 2 (2,2,6,6-tetramethyl-3,5-heptanedionate) 2 ,   wherein O-i-Pr is isopropoxy.   
     
     
         6 . The precursor composition of  claim 1 , wherein each of the lead, zirconium and titanium precursors is in a same solvent medium. 
     
     
         7 . The precursor composition of  claim 1 , wherein each of the lead, zirconium and titanium precursors is in a different solvent medium. 
     
     
         8 . The precursor composition of  claim 1 , wherein the solvent mediums of the respective lead, zirconium and titanium precursors include solvent selected from the group consisting of glymes, diglymes, hydrocarbon solvents, aryl solvents, aliphatic hydrocarbons, aromatic hydrocarbons, isopropanol, organic ethers, organic esters, alkyl nitriles, alkanols, alcohols, organic amines, polyamines, glymes having from 1 to 20 ethoxy —(C 2 H 4 O)— repeat units; C 2 -C 12  alkanols, dialkyl ethers comprising C 1 -C 6  alkyl moieties, C 4 -C 8  cyclic ethers; C 12 -C 60  crown O 4 -O 20  ethers; C 6 -C 12  aliphatic hydrocarbons; C 6 -C 18  aromatic hydrocarbons, tetrahydrofuran, alkyl acetate, tetraglyme, C 3 -C 8  alkanols, butyl acetate, 12-crown-4, 15-crown-5, and 18-crown-6 ethers, acetone, dimethoxyethane (DME), dimethylformamide (DMF), polyether alcohols, tetrathiocyclodecane, tetrahydrofuranacetate, octane, decane, and mixtures of two or more of the foregoing. 
     
     
         9 . The precursor composition of  claim 1 , wherein at least one of the solvent mediums of the respective lead, zirconium and titanium precursors includes a solvent selected from the group consisting of tetrahydrofuran, glyme solvents, alcohols, hydrocarbon solvents, aryl solvents, amines, polyamines, and mixtures of two or more of the foregoing. 
     
     
         10 . The precursor composition of  claim 1 , wherein at least one of the solvent mediums of the respective lead, zirconium and titanium precursors includes a solvent selected from the group consisting of tetrahydrofuran, isopropanol, tetraglyme, octane, decane, and polyamine, and mixtures of two or more of the foregoing. 
     
     
         11 . The precursor composition of  claim 1 , wherein at least one of the solvent mediums of the respective lead, zirconium and titanium precursors includes a solvent selected from the group consisting of glyme, diglyme, isopropanol, tetrahydrofuran, tetraglyme, butyl acetate, acetone, dimethoxyethane, dimethylformamide, tetrathiocyclodecane, tetrahydrofuranacetate, octane, decane, and mixtures of two or more of the foregoing. 
     
     
         12 . The precursor composition of  claim 1 , wherein the lead, zirconium and titanium precursors are selected from the group consisting of:
 (i) lead bis(2,2,6,6-tetramethyl-3,5-heptanedionate), Ti(O-i-Pr) 2 (2,2,6,6-tetramethyl-3,5-heptanedionate) 2 , and zirconium tetrakis(2,2,6,6-tetramethyl-3,5-heptanedionate) as respective lead, titanium and zirconium precursors;   (ii) lead bis(2,2,6,6-tetramethyl-3,5-heptanedionate) N,N′,N″-pentamethyl diethylenetriamine, Ti(O-i-Pr) 2 (2,2,6,6-tetramethyl-3,5-heptanedionate) 2 , and zirconium tetrakis(2,2,6,6-tetramethyl-3,5-heptanedionate) as respective lead, titanium and zirconium precursors; and   (iii) lead bis(2,2,6,6-tetramethyl-3,5-heptanedionate) N,N′,N″-pentamethyl diethylenetriamine, Ti(O-i-Pr) 2 (2,2,6,6-tetramethyl-3,5-heptanedionate) 2 , and zirconium bis(isopropoxide)bis(2,2,6,6-tetramethyl-3,5-heptanedionate) as respective lead, titanium and zirconium precursors;   wherein O-i-Pr is isopropoxy.   
     
     
         13 . A precursor composition for forming a PZT film on a substrate by liquid delivery MOCVD, said precursor composition comprising lead, zirconium and titanium precursors each in a solvent medium so that the precursors when vaporized form precursor vapor which when contacted with the substrate forms a film having an A/B ratio of from 0.612 to 1.53, wherein the A/B ratio is Pb to (Zr+Ti). 
     
     
         14 . The precursor composition of  claim 13 , wherein at least one of the solvent mediums of the respective lead, zirconium and titanium precursors include solvent selected from the group consisting of glymes, diglymes, hydrocarbon solvents, aryl solvents, aliphatic hydrocarbons, aromatic hydrocarbons, isopropanol, organic ethers, organic esters, alkyl nitriles, alkanols, alcohols, organic amines, polyamines, glymes having from 1 to 20 ethoxy —(C 2 H 4 O)— repeat units; C 2 -C 12  alkanols, dialkyl ethers comprising C 1 -C 6  alkyl moieties, C 4 -C 8  cyclic ethers; C 12 -C 60  crown O 4 -O 20  ethers; C 6 -C 12  aliphatic hydrocarbons; C 6 -C 18  aromatic hydrocarbons, tetrahydrofuran, alkyl acetate, tetraglyme, C 3 -C 8  alkanols, butyl acetate, 12-crown-4, 15-crown-5, and 18-crown-6 ethers, acetone, dimethoxyethane (DME), dimethylformamide (DMF), polyether alcohols, tetrathiocyclodecane, tetrahydrofuranacetate, octane, decane, and mixtures of two or more of the foregoing. 
     
     
         15 . The precursor composition of  claim 13 , wherein at least one of the solvent mediums of the respective lead, zirconium and titanium precursors includes solvent selected from the group consisting of tetrahydrofuran, glyme solvents, alcohols, hydrocarbon solvents, aryl solvents, amines, polyamines, and mixtures of two or more of the foregoing. 
     
     
         16 . The precursor composition of  claim 13 , wherein at least one of the solvent mediums of the respective lead, zirconium and titanium precursors includes a solvent selected from the group consisting of glyme, diglyme, isopropanol, tetrahydrofuran, tetraglyme, butyl acetate, acetone, dimethoxyethane, dimethylformamide, tetrathiocyclodecane, tetrahydrofuranacetate, octane, decane, and mixtures of two or more of the foregoing. 
     
     
         17 . A precursor composition for forming a PZT film on a substrate by liquid delivery MOCVD, said precursor composition comprising lead, zirconium and titanium precursors each in a solvent medium so that the precursors when vaporized form precursor vapor which when contacted with the substrate forms a film that is at least one of dimensional scalable, pulse length scalable and E-field scalable. 
     
     
         18 . The precursor composition of  claim 17 , wherein at least one of the solvent mediums of the respective lead, zirconium and titanium precursors includes a solvent selected from the group consisting of glymes, diglymes, hydrocarbon solvents, aryl solvents, aliphatic hydrocarbons, aromatic hydrocarbons, isopropanol, organic ethers, organic esters, alkyl nitriles, alkanols, alcohols, organic amines, polyamines, glymes having from 1 to 20 ethoxy —(C 2 H 4 O)— repeat units; C 2 -C 12  alkanols, dialkyl ethers comprising C 1 -C 6  alkyl moieties, C 4 -C 8  cyclic ethers; C 12 -C 60  crown O 4 -O 20  ethers; C 6 -C 12  aliphatic hydrocarbons; C 6 -C 18  aromatic hydrocarbons, tetrahydrofuran, alkyl acetate, tetraglyme, C 3 -C 8  alkanols, butyl acetate, 12-crown-4, 15-crown-5, and 18-crown-6 ethers, acetone, dimethoxyethane (DME), dimethylformamide (DMF), polyether alcohols, tetrathiocyclodecane, tetrahydrofuranacetate, octane, decane, and mixtures of two or more of the foregoing. 
     
     
         19 . The precursor composition of  claim 17 , wherein at least one of the solvent mediums of the respective lead, zirconium and titanium precursors includes solvent selected from the group consisting of tetrahydrofuran, glyme solvents, alcohols, hydrocarbon solvents, aryl solvents, amines, polyamines, and mixtures of two or more of the foregoing. 
     
     
         20 . The precursor composition of  claim 17 , wherein at least one of the solvent mediums of the respective lead, zirconium and titanium precursors includes a solvent selected from the group consisting of glyme, diglyme, isopropanol, tetrahydrofuran, tetraglyme, butyl acetate, acetone, dimethoxyethane, dimethylformamide, tetrathiocyclodecane, tetrahydrofuranacetate, octane, decane, and mixtures of two or more of the foregoing.