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 device comprising:
a bit line; a word line; a first data line; a first electrode; a first insulating film between the first electrode and the first data line; a second data line; a second electrode; a second insulating film between the second electrode and the second data line a third insulating film between the first data line and the second electrode; and a 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, wherein the other of the source and the drain of the transistor is electrically connected to the first electrode and the second electrode, wherein a gate of the transistor is electrically connected to the word line, and wherein the first electrode is provided over a step portion.