Coating processes – Direct application of electrical – magnetic – wave – or... – Pretreatment of substrate or post-treatment of coated substrate
Patent
1992-10-20
1994-12-13
Padgett, Marianne
Coating processes
Direct application of electrical, magnetic, wave, or...
Pretreatment of substrate or post-treatment of coated substrate
427554, 427559, 427 80, 4273764, 4273767, 4273762, B05D 306, B05D 512, B05D 302
Patent
active
053728599
ABSTRACT:
Thin film ferroelectric capacitors (10) comprising a ferroelectric film (18) sandwiched between electrodes (16 and 20) for nonvolatile memory operations are rendered more stable by subjecting the capacitors to an anneal following deposition of the top electrode (20). The anneal is done so as to form the interface (22) between the ferroelectric film and the top electrode. Heating in an air oven, laser annealing, or electron bombardment may be used to form the interface. Heating in an air oven is done at a temperature at least equal to the crystallization temperature of the ferroelectric film. Where the ferroelectric film comprises lead zirconate titanate, annealing is done at about 550.degree. to 600.degree. C. for about 10 to 15 minutes. The formation treatment reduces the magnitude of charge associated with the non-switching pulse in the thin film ferroelectric capacitors. Reduction of this charge leads to significantly more stable nonvolatile memory operations in both digital and analog memory devices. The formation treatment also reduces the ratio of change of the charge associated with the non-switching pulse as a function of retention time. These improved memory devices exhibit greater performance in retention and reduced fatigue in memory arrays.
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Jones Thomas H.
Kusmiss John H.
Miller Guy M.
Padgett Marianne
The United States of America as represented by the Administrator
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