Semi-floating gate FET

A method of making a vertical semi-floating gate transistor, the method comprising:

• forming on a silicon substrate, a stack of silicon layers having various doping concentrations;
• patterning a fin in the stack to form a source and a channel of the transistor, the channel disposed over the source;
• forming a drain on the fin;
• after forming the drain, forming a semi-floating gate adjacent to the fin, the semi-floating gate coupled to and forming a P-N junction at a sidewall of the fin;
• forming a control gate abutting top and side surfaces of the semi-floating gate;
• and
• forming a sidewall spacer adjacent to the control gate.

A method, comprising:

• patterning a channel structure from a layered stack on a substrate, the channel structure extending away from a surface of the substrate, the channel structure including:
• a first portion of a source;
• and
• a first channel;
• forming a P-N junction at a sidewall of the channel structure by forming a semi-floating gate structure abutting the channel structure;
• forming a second channel on the first channel;
• forming a control gate structure on top and sides of the semi-floating gate structure;
• and
• forming a drain overlying the first portion of the source, the drain separated from the first portion of the source by the first channel and the second channel.

A method, comprising:

• patterning a channel structure from a layered stack on a substrate, the channel structure extending away from a surface of the substrate, the channel structure including:
• a first portion of a source;
• a channel;
• and
• a semiconductor layer between the source and the channel;
• forming a semi-floating gate structure abutting the channel structure, the forming the semi-floating gate structure including forming a P-N junction at a sidewall of the channel structure;
• forming a control gate structure on top and sides of the semi-floating gate structure;
• and
• forming a drain overlying the first portion of the source, the drain separated from the first portion of the source by the channel.