Scalable lead zirconium titanate (PZT) thin film material and deposition method, and ferroelectric memory device structures comprising such thin film material
View Patent ↗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).
1. A flash vaporization liquid delivery process for depositing a lead zirconium titanate ferroelectric material that is at least one of dimensional scalable, pulse length scalable and E-field scalable, said process comprising:
providing lead, zirconium and titanium precursors in liquid medium;
flash vaporizing the lead, zirconium and titanium precursors in liquid medium, to form precursor vapor; and
contacting the precursor vapor with a substrate under vapor deposition conditions to deposit thereon lead zirconium titanate ferroelectric material that is at least one of dimensional scalable, pulse length scalable and E-field scalable.
2. The process of claim 1 , wherein the lead, zirconium and titanium precursors do not undergo ligand exchange or have degenerate exchange.
3. The process of claim 1 , wherein said lead precursor is selected from among Pb(thd) 2 and Pb(thd) 2 pmdeta.
4. The process of claim 1 , wherein said zirconium precursor is selected from among Zr(thd) 4 and Zr(O-i-Pr) 2 (thd) 2 .
5. The process of claim 1 , wherein said titanium precursor is Ti(O-i-Pr) 2 (thd) 2 .
6. The process of claim 1 , wherein the lab, zirconium and titanium precursors comprise Pb(thd) 2 , Ti(O-i-Pr) 2 (thd) 2 and Zr(thd) 4 , respectively.
7. The process of claim 1 , wherein the lab, zirconium and titanium precursors comprise Pb(thd) 2 pmdeta, Ti(O-i-Pr) 2 (thd) 2 and Zr(thd) 4 , respectively.
8. The process of claim 1 , wherein the lab, zirconium and titanium precursors comprise Pb(thd) 2 pmdeta, Ti(O-i-Pr) 2 (thd) 2 and Zr(O-i-Pr) 2 (thd) 2 , respectively.
9. The process of claim 1 , wherein the liquid medium comprises one or more solvent species selected from the group consisting of: tetrahydrofuran, glyme solvents, alcohols, hydrocarbon solvents, hydroaryl solvents, amines, polyamines, and mixtures of two or more of the foregoing.
10. The process of claim 1 , wherein the liquid medium comprises tetrahydrofuran: isopropanol: tetraglyme in an 8:2:1 volume ratio.
11. The process of claim 1 , wherein the liquid medium comprises octane:decane:polyamine in a 5:4:1 volume ratio.
12. The process of claim 1 , wherein the liquid medium comprises octane:polyamine in a 9:1 volume ratio.
13. The process of claim 1 , wherein the liquid medium comprises tetrahydrofuran.
14. The process of claim 1 , wherein the substrate comprises a noble metal selected from the group consisting of iridium, platinum, and combinations thereof.
15. The process of claim 1 , wherein the substrate comprises a TiAlN barrier layer overlaid by an iridium layer.
16. The process of claim 1 , wherein the precursor vapor is connected to the contacting in a carrier gas.
17. The process of claim 16 , wherein the carrier gas is selected from the group consisting of argon, helium and mixtures thereof.
18. The process of claim 1 , further comprising flowing to the contacting an oxidant medium including at least one species selected from the group consisting of O 2 , O 3 , N 2 O, and O 2 /N 2 O.
19. The process of claim 1 , wherein the lead zirconium titanate material forms a capacitor of a microelectronic device.
20. The process of claim 1 , wherein said contacting comprises conditions of temperature in a range of from about 400° C. to about 1200° C., and pressure in a range of from about 0.1 to about 760 Torr.