Use of calcium and strontium dopants to improve retention perfor

Details Use of calcium and strontium dopants to improve retention perfor Use of calcium and strontium dopants to improve retention perfor

1996-03-15

1999-10-19

Kincaid, Kristine

Electricity: electrical systems and devices

Electrostatic capacitors

Fixed capacitor

3613214, 3613215, 257295, H01G 406

Patent

active

059699353

ABSTRACT:
A lead zirconate titanate ferroelectric film used as the dielectric layer in a ferroelectric capacitor is doped with calcium and/or strontium, and the lead composition selected to improve data retention performance. The chemical formula for the ferroelectric film is: (Pb.sub.v Ca.sub.w Sr.sub.x La.sub.y)(Zr.sub.z Ti.sub.(1-z))O.sub.3 ; wherein v is ideally between 0.9 and 1.3; w is ideally between 0 and 0.1; x is ideally between 0 and 0.1; y is ideally between 0 and 0.1, and z is ideally between 0 and 0.9. In addition, the chemical composition of the ferroelectric film is further specified in that the measured opposite state charge at a specific time and temperature of the ferroelectric capacitor is greater than eight micro-Coulombs per square centimeter, and the rate of imprint degradation is less than fifteen percent per decade.

REFERENCES:
patent: 2911370 (1959-11-01), Kulcsar
patent: 3179594 (1965-04-01), Kulcsar et al.
patent: 4124671 (1978-11-01), Walker et al.
patent: 4626369 (1986-12-01), Walker, Jr.
patent: 5104690 (1992-04-01), Greenwald
patent: 5112433 (1992-05-01), Dawson et al.
patent: 5281888 (1994-01-01), Takeuchi et al.
patent: 5337279 (1994-08-01), Gregory et al.
patent: 5338999 (1994-08-01), Ramakrishna et al.
patent: 5376857 (1994-12-01), Takeuchi et al.
patent: 5378382 (1995-01-01), Nichimura et al.
M. Huffman, et al., "Morphology and Electrical Characterization of Calcium Modified Ferroelectric Lead Zirconate Titanate Films", Ferroelectrics, vol. 143, pp. 252-262, .COPYRGT.1993.
Kulcsar, F., "Electromechanical Properties of Lead Titanate Zirconate Ceramics with Lead Partially Replaced by Calcium or Strontium," Journal of the American Ceramic Society, Jan. 1959, pp. 49-51, Westerville, Ohio.
Jaffe, B., et al., "Piezoelectric Ceramics," 1971, Academic Press, New York, New York.
Atkin, R.B., "Performance of Sputtered Pb.sub.0.92 Bi.sub.0.07 La.sub.0.01 (Fe.sub.0.0405 Nb.sub.0.325 Zr.sub.0.27)O.sub.3 Ferroelectric Memory Films," Ferroelectrics 1972, vol. 3, pp. 213-215, Norwich, England.
Sharma, B.S., et al., "Retention in Thin Ferroelectric Films," Ferroelectrics 1973, vol. 5, pp. 69-75, Norwich, England.
Mehta, R.R., et al., "Depolarization Fields in Thin Ferroelectric Films," Journal of Applied Physics, vol. 44, No. 8, Aug. 1973, pp. 3379-3385, Woodbury, New York
Yamaka, E., et al., "Structural, Ferroelectric, and Pyroelectric Properties of Highly C-Axis Oriented Pb.sub.1-x Ca.sub.x TiO.sub.3 Thin Film Grown by Radio-Frequency Magnetron Sputtering," Journal of Vacum Science Technology, Sep./Oct. 1988, pp. 2921-2928, College Park, Maryland.
Shepherd, W.H., "Fatigue and Aging in Sol-Gel Derived PZT Thin Films," Materials Research Society Symposium Proceedings vol. 200, 1990, pp. 277-289, Pittsburgh, Pennsylvania.
Abt, N., "Electrical Measurement of Ferroelectric Capacitors for Non-Volatile Memory Applications," Materials Research Society Symposium Proceedings vol. 200, 1990, pp. 303-312, Pittsburgh, Pennsylvania.
Kulkarni, J., et al., "Ageing of Volatile and Non-Volatile Components of the Remnant Polarization in PZT," Proceedings of the International Symposium on Integrated Ferroelectrics (1992), pp. 363-369, National Semiconductor Corp., Santa Clara, California.
Huffman, M., et al., "Morphology and Electrical Characterization of Calcium Modified Ferroelectric Lead Zirconate Titanate Films," Ferroelectrics, 1993, v. 143, n. 1/4, pp. 251-262, Norwich, England.
Dat, R., et al., "Imprint Testing of Ferroelectric Capacitors Used for Non-Volatile Memories," Integrated Ferroelectrics, 1994, vol. 5, pp. 275-286, Amsterdam B.V.
Evans, J.T. Jr., et al., "The Imprint Mechanism in Ferroelectric Capacitors," Proceedings of the International Symposium on Integrated Ferroelectrics (1995), Radiant Technologies, Inc., Albuquerque, New Mexico.
Lee, J., et al., "Imprint of (Pb,La)(Zr,Ti)O.sub.3 Thin Films With Various Crystalline Qualities," Applied Physics Letter, vol. 68, No. 4, Jan. 22, 1996, Woodbury, New York.

Affiliated with

Also associated with

Rating

Use of calcium and strontium dopants to improve retention perfor does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Use of calcium and strontium dopants to improve retention perfor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Use of calcium and strontium dopants to improve retention perfor will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2064083