Ferroelectric memory device and their manufacturing methods
US6171871A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 14, 1998 |
| Grant date | Jan 9, 2001 |
| Priority date | — |
| Expiry date | May 14, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L21/02282
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
It is intended to provide a ferroelectric that exhibits superior ferroelectricity. A ferroelectric provided is an oxide having a layered crystal structure that is composed of Bi, a first element Me, a second element R, and O. The first element Me is at least one element selected from the group consisting of Na, K, Ca, Ba, Sr, Pb, and Bi. The second element R is at least one element selected from the group consisting of Fe, Ti, Nb, Ta, and W. Ninety-eight percent or more of the entire body of the ferroelectric exhibits ferroelectricity. After an oxide having a layered crystal structure has been grown by a vapor-phase method (crystal growth step), electrodes are attached to the oxide having a layered crystal structure and a voltage is applied thereto (voltage application step). As a result, strains of crystal lattices are corrected at least partially, whereby portions that did not exhibit ferroelectricity at all or did not exhibit superior ferroelectricity due to such large strains that the symmetry of crystal lattices is lost are changed so as to exhibit superior ferroelectricity.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.