Semiconductor device and method of fabricating the same, and nand gate circuit using the semiconductor device

A method comprising:

• forming a channel region in a semiconductor substrate;
• forming a first gate electrode and a second gate electrodes over the semiconductor substrate, the first gate electrode and the second gate electrode being spaced apart from each other at a predetermined distance;
• forming spacers on sidewalls of the first gate electrode and the second gate electrode and over the semiconductor substrate;
• forming source/drain regions in the semiconductor substrate;
• forming a first interlayer insulating layer and a second interlayer insulating over the semiconductor substrate;
• forming a plurality of contact holes in the first interlayer insulating layer and the second interlayer insulating;
• and then
• forming a contact plug in the plurality of contact holes.

A method comprising:

• providing a switching element including a transistor having a plurality of gates;
• applying a first input signal to a first gate of the transistor;
• applying a second input signal to a second gate of the transistor;
• grounding a drain of the transistor;
• connecting a source of the transistor to an output terminal;
• and then
• controlling the channel according to the first input signal and the second input signal by forming the channel between the drain and the source.