Semiconductor integrated circuit having anti-fuse, method of fabricating, and method of writing data in the same

A semiconductor integrated circuit comprising:

• a semiconductor substrate having a surface;
• a first and a second MOS transistor formed on the surface of the semiconductor substrate, each of the first and the second MOS transistors comprising:
• a first conductivity type source and drain region, and
• a second conductivity type channel region between the source and drain regions, the first MOS transistor having a first drain-source breakdown voltage and the second MOS transistor having a second drain-source breakdown voltage lower than the first drain-source breakdown voltage;
• and
• a writing circuit integrated on the surface of the semiconductor substrate, the writing circuit supplying a writing voltage between the drain and the source regions of the second MOS transistor to make the second MOS transistor permanently conductive between the source and the drain regions thereof