| 摘要 |
PROBLEM TO BE SOLVED: To make a specific dielectric constant maximum, by using a dielectric thin film with a ferroelectric phase transition point on a give temperature range. SOLUTION: A capacitor part made up of a dielectric film selected by a cell-selecting transistor part, and upper and lower electrodes with the dielectric film in between. A voltage through a wire 10 is applied to the electrodes of the capacitor part to accumulate charge. The function of memory cell is carried out by using a change in the accumulating and discharging step with the wire 10. A specific dielectric constant of oxide dielectric material depends greatly on temperatures, especially in a material with property of ferroelectric phase transition, the specific dielectric constant becomes a maximum at a temperature of phase transition and becomes smaller by about one place at temperatures other than the vicinity temperature at the phase transfer. There are few dielectric material with a single body having a maximum specific dielectric constant at temperatures from 0 to 80 deg.C. In this case, a dielectric material made of BTS15 is used, and thereby a cell area becomes smaller than one sixth of a conventional one. |
