Semiconductor memory device

摘要

To increase a storage capacity of a memory module per unit area, and to provide a memory module with low power consumption, a transistor formed using an oxide semiconductor film, a silicon carbide film, a gallium nitride film, or the like, which is highly purified and has a wide band gap of 2.5 eV or higher is used for a DRAM, so that a retention period of potentials in a capacitor can be extended. Further, a memory cell has n capacitors with different capacitances and the n capacitors are each connected to a corresponding one of n data lines, so that a variety of the storage capacitances can be obtained and multilevel data can be stored. The capacitors may be stacked for reducing the area of the memory cell.

主权项

1. A semiconductor memory device comprising:
a bit line; a word line; n data lines (n is a natural number of 2 or more); and a memory cell including a transistor and n capacitors, the transistor having a channel in an oxide semiconductor film, wherein:
one of a source and a drain of the transistor is electrically connected to the bit line,the other of the source and the drain of the transistor is electrically connected to one electrode of each of the n capacitors,a gate of the transistor is electrically connected to the word line, andthe other electrode of each of the n capacitors is electrically connected to a corresponding one of the n data lines.