| 摘要 |
PROBLEM TO BE SOLVED: To prevent erroneous inversion of data by applying a read voltage within such range as causing no inversion of polarization in a ferroelectric film. SOLUTION: A gate insulation film 21, a lower electrode 31, a ferroelectric film 22 and an upper electrode 32 are formed sequentially on a substrate 10. When a data is read out from such ferroelectric memory, a read voltage VR is applied between the upper electrode 32 and a drain 12 utilizing the residual polarizaiton of ferroelectric film 22 and '1' or '0' is determined depending on the fact whether a current flows between the source 11 and the drain 12 or not. In this regard, the read voltage VR is applied within such range as causing no inversion of polarization in the ferroelectric film. For example, 0V is applied to the gate 31, source 11 and substrate 10 and a voltage VR, satisfying a formula|VR|< (CF+Co)/Co}.|Vc|, is applied to the drain 12. In the formula, CF is the capacitance (fF) of ferroelectric film 22, Co is the capacitance (fF) between the lower electrode 31 and the drain 12, and Vc is the coercive voltage (V) of ferroelectric film 22.
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