MOCVD and annealing processes for C-axis oriented...

Semiconductor device manufacturing: process – Having magnetic or ferroelectric component

Reexamination Certificate

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C438S240000, C438S250000, C438S253000, C438S393000, C438S396000, C257S295000

Reexamination Certificate

active

06475813

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to the fabrication of ferroelectric memory devices, and more particularly to the use of specifically oriented ferroelectric thin films which exhibit both very good ferroelectric properties and lower surface roughness.
BACKGROUND OF THE INVENTION
The use of ferroelectric thin films in non-volatile memories has drawn much attention in recent years, primarily due to the bi-stable nature of these films, i.e., these films have two predominant polarization directions. Most of the studies of Ferroelectric Random Access Memories (FRAMs) have concentrated on structures having one transistor and one capacitor. The capacitor is made of a thin ferroelectric film sandwiched between two conductive electrodes. The circuit configuration and read/write sequence of this type memory are similar to that of DRAMs, except that data refreshing is not necessary in FRAMs.
Another aspect of ferroelectric non-volatile memory formation is to determine the best technique for deposition of a ferroelectric thin film directly onto the gate area of a FET and to form a ferroelectric-gate controlled FET (FGCFET). Ferroelectric-gate-controlled devices, such as metal-ferroelectric-silicon (MFS) FETs, have been proposed as early as the 1950s, and various modified MFSFET structures have been proposed, for example, metal-ferroelectric-insulator-silicon (MFIS) FETs, metal-ferroelectric-metal-silicon (MFMS) FETs, and metal-ferroelectric-metal-oxide-silicon (MFMOS) FETs.
In order to meet the requirements of FRAMs applications, however, specifically oriented ferroelectric thin films are needed. Experimental results demonstrate that, using metal organic chemical vapor deposition (MOCVD) processes, high oriented, i.e., wherein the ration of c-axis peak-to-random peak is larger than 80%, ferroelectric thin films always have an unacceptable surface roughness because of the growth process using MOCVD.
SUMMARY OF THE INVENTION
A method of fabricating a c-axis ferroelectric thin film includes preparing a substrate; depositing a layer of ferroelectric material by metal organic chemical vapor deposition, including using a precursor solution having a ferroelectric material concentration of about 0.1 M/L at a vaporizer temperature of between about 140° C. to 200° C.; and annealing the substrate and the ferroelectric material at a temperature between about 500° C. to 560° C. for between about 30 minutes to 120 minutes.
An object of the invention is to provide fabrication processes, such as MOCVD and annealing, for ferroelectric thin films having a preferred orientation.
Another object of the invention is to provide a ferroelectric thin film having minimal surface roughness, uniform surface morphology and improved ferroelectric properties through the use of multiple MOCVD and annealing processes.
This summary and objectives of the invention are provided to enable quick comprehension of the nature of the invention. A more thorough understanding of the invention may be obtained by reference to the following detailed description of the preferred embodiment of the invention in connection with the drawings.


REFERENCES:
patent: 3717562 (1973-02-01), Schinke et al.
patent: 5111186 (1992-05-01), Narlow et al.
patent: 5257009 (1993-10-01), Norlow
patent: 6110531 (2000-08-01), Paz de Araujo et al.
patent: 6190925 (2001-02-01), Li et al.
patent: 6229166 (2001-05-01), Kim et al.
patent: 6281022 (2001-08-01), Li et al.
Zhang et al. “Phase and Microstructure Analysis of Lead Germanate Thin Film Deposited by Metalorganic Chemical Vapor Depostion” Jpn. J. Appl. Phys. vol. 23., Jan. 1999, pp L59-L61.*
United States Patent Application Publication US 2001/0024835 A1 (ser. No. 09/814723) Li et al. Sep. 27, 2001.*
Article entitled, “Processing of a Uniaxial Ferroelectric Pb5Ge3O11Thin Film at 450°C with C-Axis Orientation”, by J.J. Lee and S.K. Dey, published in Appl. Phys. Lett. 60 (2), May 18, 1992, pp. 2487-2488.
Article entitled, “Ferroelectric and Optical Properties of Pb5Ge3O11and its Isomorphous Compound Pb5Ge3SiO11”, by H. Iwasaki, S. Miyazawa, H. Koizumi, K. Sugii & N. Niizeki, published in J. Appl. .Phys., vol. 43, No. 12, Dec. 1972, pp. 4907-4915.
Article entitled, Electro-optic Properties of Ferroelectric 5PbO—3GeO2Single Crystal, by N. Uchida, T. Saku, H. Iwasaki & K. Onuki, published in J. Appl. Phys., vol. 43, No. 12, Dec. 1972, pp. 4933-4936.
Article entitled, “Oriented Lead Germanate Thin Films by Excimer Laser Ablation”, by C.J. Peng, D. Roy and S.B. Krupanidhi, published in Appl. Phys. Lett. 60 (7), Feb. 17, 1992, pp. 827-829.
Article entitled, Evolution of Ferroelectricity in Ultrafine-grained Pb5Ge3O11Crystallized from the Glass, by A.M. Glass, K. Nassau & J.W. Shiever, published in J. Appl. Phys. 48(12) Dec. 1977, pp. 5213-5216.
Article entitled, 5PbO-3GeO2Crystal; A New Ferroelectric, by H. Iwasaki, K. Sugii, T. Yamada & N. Niizeki, published in Appl. Phys., vol. 18, No.;. 10, May 15, 1971, pp. 444-445.
Article entitled, Elastic and Piezoelectric Properties of Ferroelectric 5PbO—3GeO2Crystals, by T. Yamada, H. Iwasaki & N. Niizeki, published in J. Appl. Phys. vol. 43, No. 3, Mar., 1972, pp. 771-775.
Article entitled, Electrical and Structural Properties of Flash-Evaporated Ferroelectric Lead Germanate Films on Silicon, by A. Mansingh & S.B. Krupanidni, published in Thin Solid Films,80(1981) pp. 359-371.
Article entitled Preparation and Properties of Thermally Evaporated Lead Germanate Films, by A. Mansingh & S.B. Krupanidhi, published in J. Appl. Phys. 51(10), Oct. 1980, pp. 5408-5412.
Zwicker et al., “Formation of secondary Phase during Crystal Growth of Pb5Ge3011,” J. of Electr. Mater., 6(2), p125.*
Haegawa et al., “Phase Relations and Crystallization of Glass in the System PbO-GeO2,” J. of Mater. Science, 8 (12), p. 1725-1730.

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