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  Low voltage drive ferroelectric capacitorUSPTO Application #: 20060038214Title: Low voltage drive ferroelectric capacitor Abstract: A method of forming a low-voltage drive thin film ferroelectric capacitor includes the steps of depositing a ferroelectric and platinum thin film dielectric layer over a bottom electrode, annealing the dielectric layer, wherein a nanocomposite layer is formed including nanoparticles of platinum and forming a top electrode over the dielectric layer. An integrated circuit is also provided including a ferroelectric capacitor. The capacitor includes a bottom electrode formed over a substrate and a ferroelectric and platinum thin film nanocomposite dielectric layer formed over the bottom electrode, wherein the nanocomposite layer includes nanoparticles of platinum. A top electrode is formed over the dielectric layer. (end of abstract) Agent: Duane Morris, LLPIPDepartment - Philadelphia, PA, US Inventors: Yuan-Chieh Tseng, Chao-Hsiung Wang, Tai-Bor Wu USPTO Applicaton #: 20060038214 - Class: 257295000 (USPTO) Related Patent Categories: Active Solid-state Devices (e.g., Transistors, Solid-state Diodes), Field Effect Device, Having Insulated Electrode (e.g., Mosfet, Mos Diode), With Ferroelectric Material Layer The Patent Description & Claims data below is from USPTO Patent Application 20060038214. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATION [0001] This application is a divisional application of U.S. patent application Ser. No. 10/313,776 entitled "Method of Forming a Low Voltage Drive Ferroelectric Capacitor" filed Dec. 6, 2002, now U.S. Pat. No. ______, the entirety of which is hereby incorporated by reference herein. FIELD OF THE INVENTION [0002] The present invention relates to integrated circuits and more particularly to integrated circuits including ferroelectric capacitors and method of manufacturing the same. BACKGROUND OF THE INVENTION [0003] Ferroelectric materials such as lead zirconate titanate (PZT) are utilized in forming ferroelectric capacitors. These capacitors are then used in the formation of ferroelectric RAM (FRAM) devices due to the capacitors' electrical properties of retention, read/write endurance, and speed of the write cycle. [0004] As memory integrated circuits become more dense, low voltage operation becomes increasingly more important. Traditional methods of improving the polarization switching property of ferroelectric materials, such PZT, focus on changing the composition of the PZT by adding soft dopants such as Vanadium, Lead or other dopants. Lanthanum (La) doping has also been proposed as described in B. Yang, et al., "Low Voltage Performance of Pb(Zr,Ti)O.sub.3 Capacitors Through Donor Doping," Applied Physics Letters, Vol. 71(24), Dec. 15, 1997. However, this approach has only pushed the driving voltage of the polarization switching down to between 1.5 to 2.0 volts. This, in turn, restricts the required voltage drive of FRAM devices to that range. [0005] More recently, it was reported in N. Duan et al., "Enhancement of Dielectric and Ferroelectric Properties by Addition of Pt Particles to a Lead Zirconate Titanate Matrix," Applied Physics Letters, Vol. 77(20), Nov. 13, 2000, that large amounts of platinum particles in a PZT matrix can result in improvements in the dielectric and ferroelectric properties of a PZT composite. A powder PZT/Pt composite was prepared by conventional solid state reaction by sintering of mixed powders, and dense compacts were formed from the composite for testing. The PZT/Pt composite material proposed by the article, however, is not a thin film. A thin film generally has a thickness that ranges from 1.0 nanometer to 1 micron. (K. N. Tu, et al., Electronic Thin Film Science: For Electronical Engineers and Materials Sciences, p. 1 (Macmillan Publishing Co. 1992). Rather, the PZT/Pt composite is a bulk material that contains micron-sized or larger particles of platinum in the PZT matrix. The bulk material is not suitable for forming ferroelectric capacitors in integrated circuits or FRAM devices. In ULSI technology, a ferroelectric film thicker than 1 .mu.m (10,000 .ANG.) in an integrated circuit has several disadvantages, including: (1) high cost; (2) difficult integration when a device is scaled down; and (3) difficulty in achieving low voltage applications. [0006] Therefore, there remains a need for an improved ferroelectric capacitor, particularly a thin film ferroelectric capacitor, with improved polarization switching characteristics under low voltage drive and a method of manufacturing the same. SUMMARY OF THE INVENTION [0007] A method of forming a low-voltage drive thin film ferroelectric capacitor includes the steps of depositing a ferroelectric and platinum thin film dielectric layer over a bottom electrode, annealing the dielectric layer, wherein a nanocomposite layer is formed including nanoparticles of platinum and forming a top electrode over the dielectric layer. An integrated circuit is also provided including a ferroelectric capacitor. The capacitor includes a bottom electrode formed over a substrate and a ferroelectric and platinum thin film nanocomposite dielectric layer formed over the bottom electrode, wherein the nanocomposite layer includes nanoparticles of platinum. A top electrode is formed over the dielectric layer. [0008] Both the remnant polarization and dielectric constant of the thin film are significantly enhanced by the formation of platinum nanoparticles. A capacitor having low voltage drive of 1 volt or lower with high remnant polarization, such as at least 7 .mu.C/cm.sup.2, can be achieved while repressing fatigue degradation and exhibiting no significant coercive field strength or leakage current affects. Low voltage drive FRAM devices may be fabricated using the nanocomposite thin film ferroelectric capacitor structure and fabrication method. [0009] The above and other features of the present invention will be better understood from the following detailed description of the preferred embodiments of the invention that is provided in connection with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0010] The accompanying drawings illustrate preferred embodiments of the invention, as well as other information pertinent to the disclosure, in which: [0011] FIGS. 1-3 are cross-sectional views of a portion of a semiconductor substrate illustrating the formation of a ferroelectric capacitor; [0012] FIG. 4 is an illustration of a PZT and Pt co-sputtering system; [0013] FIG. 5 is a TEM picture of a thin film PZT-Pt nanocomposite structure formed according to an exemplary fabrication method described herein; [0014] FIG. 6 shows P-E curves for three fabricated thin film PZT-Pt nanocomposite ferroelectric capacitors and a pure PZT ferroelectric capacitor; [0015] FIG. 7 is a plot of the 2PR value verses driving voltage of the fabricated capacitors; [0016] FIG. 8 is a plot of the coercive field verses driving voltage of the fabricated capacitors; [0017] FIG. 9 is a plot of the leakage current characteristics of the fabricated capacitors; [0018] FIG. 10 illustrates an uncompressed and compressed PZT lattice structures. 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