8 bit per cell non-volatile semiconductor memory structure utilizing trench technology and dielectric floating gate

A non-volatile semiconductor memory device for storing up to eight-bits of information comprising:

• a semiconductor substrate of one conductivity type;
• a central bottom diffusion region having a conductivity type opposite to the conductivity type of said semiconductor substrate on top of a portion of said semiconductor substrate;
• a second semiconductor layer on top of said central bottom diffusion region, said second semiconductor layer having the same conductivity type of said semiconductor substrate;
• a right diffusion region formed in said second semiconductor layer apart from said central bottom diffusion channel thus forming a first vertical channel between said right and central bottom diffusion regions;
• a left diffusion region formed in said second semiconductor layer apart from both said right and central bottom diffusion regions thus forming a first horizontal channel between said right and left diffusion regions and a second vertical channel between said left and central bottom diffusion regions, said left, right and central bottom diffusion regions having the same conductivity type;
• left and right bottom diffusion regions having a conductivity type opposite to the conductivity type of said semiconductor substrate positioned on top of a portion of said semiconductor substrate apart from said central bottom diffusion region forming between said left and central bottom diffusion regions a left second horizontal channel and between said right and central bottom diffusion regions a right second horizontal channel;
• a trapping dielectric layer formed over exposed portions of said semiconductor substrate, left, central and right bottom diffusion regions and second semiconductor layer;
• and
• a wordline formed over said trapping dielectric layer,
• whereby each of said first and second vertical channels and first and second horizontal channels are capable of having two bits of information programmed, read and erased.