Memory device having a transistor including a semiconductor oxide

摘要

To provide a memory device which can perform verification operation for detecting a memory cell whose data holding time is shorter than a predetermined length, accurately in a short time. Each memory cell includes at least a first capacitor, a second capacitor, and a transistor which functions as a switching element for controlling supply, storage, and release of charge in the first capacitor and the second capacitor. The capacitance of the first capacitor is thousand or more times the capacitance of the second capacitor, preferably ten thousand or more times the capacitance of the second capacitor. In normal operation, charge is stored using the first capacitor and the second capacitor. In performing verification operation for detecting a memory cell whose data holding time is shorter than a predetermined length, charge is stored using the second capacitor.

主权项

1. A memory device comprising:
a cell array comprising a plurality of memory cells, at least one of the plurality of memory cells comprising:
a first capacitor;a second capacitor; anda transistor, wherein one of a source electrode and a drain electrode of the transistor is directly connected to the first capacitor and the second capacitor, wherein a capacitance of the first capacitor is larger than a capacitance of the second capacitor, and wherein the transistor comprises an oxide semiconductor film.