Semiconductor memory device including a memory cell comprising a D/A converter

摘要

A nonvolatile semiconductor device is provided. Each memory cell in a semiconductor device includes a D/A converter and an amplifier transistor. An output voltage of the D/A converter is stored as data in the memory cell, whereby two or more bits of data can be stored in the memory cell. By stacking transistors of the D/A converter with an interlayer film provided therebetween and using the parasitic resistance of a conductive material provided in a contact hole formed in the interlayer film as a resistor of the D/A converter, the area of the memory cell can be reduced. The transistor includes an oxide semiconductor in a channel formation region. Accordingly, a nonvolatile semiconductor device can be easily obtained.

主权项

1. A semiconductor device comprising:
a first memory cell comprising:
a first transistor;a second transistor over the first transistor;a third transistor over the second transistor;a first resistor;a second resistor; anda third resistor, wherein one of a source and a drain of the second transistor is electrically connected to a gate of the first transistor through the first resistor, and wherein one of a source and a drain of the third transistor is electrically connected to the gate of the first transistor through the second resistor and the third resistor.