Metal-insulator-semiconductor tunnel diode memory

A method, comprising:

• etching a substrate to form first, second, third, fourth, fifth and sixth protrusion regions over the substrate;
• forming first, second, and third transistors over the first, fourth, and fifth protrusion regions;
• forming a diode over the second protrusion region, wherein the diode comprises a P-doped region and an N-doped region in the second protrusion region;
• forming a first dielectric layer over the third protrusion region;
• forming an inner circular electrode and an outer ring electrode over the first dielectric layer, wherein the outer ring electrode encircles the inner circular electrode;
• forming a word line electrically coupled to gates of the first and second transistors;
• and
• forming a bit line electrically coupled to a source of the first transistor.

A method, comprising:

• forming a first transistor and a second transistor over a substrate;
• forming a dielectric layer in contact with a portion of the substrate;
• forming an inner circular electrode and an outer ring electrode in contact with a top surface of the dielectric layer, wherein the inner circular electrode is electrically connected to a source of the second transistor, and the outer ring electrode is electrically connected to a drain of the first transistor;
• forming a word line electrically coupled to a gate of the first transistor and a gate of the second transistor;
• and
• forming a bit line electrically coupled to a source of the first transistor.