Method for driving semiconductor device

摘要

It is an object to obtain a memory element (DRAM) storing multilevel data easily. The amount of charge accumulated in a capacitor of a memory element (DRAM) is controlled by changing the potential of a wiring (a bit line), which is used for writing data to the memory element (DRAM), in a period in which a transistor included in the memory element (DRAM) is on. Thus, multilevel data stored in the memory element (DRAM) can be obtained without a complex configuration of a semiconductor device including the memory element (DRAM).

主权项

1. A method for driving a semiconductor device comprising
a word line, a bit line and a memory cell comprising a transistor and a capacitor, wherein a gate of the transistor is electrically connected to the word line, wherein one of a source and a drain of the transistor is electrically connected to the bit line, and wherein the other of the source and the drain of the transistor is electrically connected to a first electrode of the capacitor, the method comprising the steps of:
turning on the transistor by changing a potential of the word line from a first potential to a second potential and then keeping the transistor on in a first period;changing a potential of the bit line from a third potential to a fourth potential and then keeping the potential of the bit line to the fourth potential in a second period; andwriting data to the memory cell by changing a third period in which the first period and the second period overlaps so that the memory cell stores multilevel data.