Ferroelectric capacitor with reduced imprint
US5677825A · kind A · utility
Inventors
Key dates
| Filing date | Dec 28, 1995 |
| Grant date | Oct 14, 1997 |
| Priority date | — |
| Expiry date | Dec 28, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10D1/682
Abstract
An improved ferroelectric capacitor exhibiting reduced imprint effects in comparison to prior art capacitors. A capacitor according to the present invention includes top and bottom electrodes and a ferroelectric layer sandwiched between the top and bottom electrodes, the ferroelectric layer comprising a perovskite structure of the chemical composition ABO.sub.3 wherein the B-site comprises first and second elements and a dopant element that has an oxidation state greater than +4. The concentration of the dopant is sufficient to reduce shifts in the coercive voltage of the capacitor with time. In the preferred embodiment of the present invention, the ferroelectric element comprises Pb in the A-site, and the first and second elements are Zr and Ti, respectively. The preferred dopant is chosen from the group consisting of Niobium, Tantalum, and Tungsten. In the preferred embodiment of the present invention, the dopant occupies between 1 and 8% of the B-sites.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.