Crystallographically aligned ferroelectric films usable in memor

Details Crystallographically aligned ferroelectric films usable in memor Crystallographically aligned ferroelectric films usable in memor

1992-03-05

1992-10-13

Griffin, Donald

Electricity: electrical systems and devices

Electrostatic capacitors

Fixed capacitor

365145, H01G 410, H01B 1200, G11C 1122

Patent

active

051556588

ABSTRACT:
A ferroelectric memory and its method of making in which a highly c-axis oriented layer (56) of ferroelectric lead zirconate titanate (PZT) is epitaxially deposited at between 640.degree. and 710.degree. C. upon a crystalline film (54) of yttrium barium copper oxide (YBCO), acting both as growth template and bottom electrode. A top electrode (58) is formed over the ferroelectric layer to complete the memory element. The two electrodes are preferably composed of the same perovskite conductor of the same cyrstalline orientation, most preferably, a-axis oriented YBCO. The structure can be grown on a silicon substrate (50) with an intermediate buffer layer (52) of yttria-stabilized zirconia. The ferroelectric behavior is optimized if the structure is cooled from its growth temperature at about 20.degree. C./min. Such a-axis oriented perovskite thin films can be grown by continuously depositing the same or different perovskite material, but dividing the deposition into three temperature stages, a first at a temperature favoring a-axis oriented growth, a second gradually increasing the temperature to a temperature favoring c-axis growth, and a third at the c-axis growth temperature. Nonetheless, a high-quality a-axis oriented film is grown. The memory can be rejuvenated after it has become fatigued by applying a pulse of magnitude equal to that of the writing pulse but of considerably longer duration.

REFERENCES:
patent: 4677336 (1987-06-01), Kushida et al.
patent: 5038323 (1991-08-01), Schwee
patent: 5046043 (1991-09-01), Miller et al.
patent: 5063539 (1991-11-01), Rallapalli
patent: 5077270 (1991-12-01), Takeda et al.
R. Ramesh et al., "Epitaxial Cuprate Superconductor/Ferroelectric Heterostructures," Science, 1991, vol. 252, pp. 944-946.
R. Ramesh et al., "Ferroelectric PbZr.sub.0.2 Ti.sub.0.8 O.sub.3 thin films on epitaxial Y-Ba-Cu-O," Applied Physics Letters, 1991, vol. 27, pp. 3542-3544.
J. F. Scott et al., "Raman spectroscopy of submicron KNO.sub.3 films. II. Fatigue and space-charge effects," Journal of Applied Physics, 1988, vol. 64, pp. 1547-1551.
A Inam et al., "a-axis oriented epitaxial YBa.sub.2 Cu.sub.3 O.sub.7-x -PrBa.sub.2 Cu.sub.3 O.sub.7-y heterostructures," Applied Physics Letters, 1990, vol. 56, pp. 2484-2486.

Affiliated with

Also associated with

Rating

Crystallographically aligned ferroelectric films usable in memor does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Crystallographically aligned ferroelectric films usable in memor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Crystallographically aligned ferroelectric films usable in memor will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1305917