Bi-directional read/program non-volatile floating gate memory cell and array thereof, and method of formation

A method of manufacturing an array of non-volatile memory cells in a substantially single crystalline semiconductive substrate of a first conductivity type, wherein said array of non-volatile memory cells has a plurality of non-volatile memory cells arranged in a plurality of rows and columns in said semiconductive substrate with each cell for storing a plurality of bits, said method comprising:

• forming spaced apart isolation regions on said semiconductive substrate that are substantially parallel to one another and extend in a said column direction, with an active region between each pair of adjacent isolation regions, wherein said semiconductive substrate has a surface;
• forming a plurality of memory cells in each of the active regions, wherein each memory cell for the storage of a plurality of bits, wherein the formation of each of the memory cells includes:
• forming a first and a second spaced apart trenches into the surface of the substrate, each of said first and second trenches having a sidewall and a bottom wall;
• forming a first region and a second region in said bottom wall of said first and second trenches, respectively, with said first region and said second region being of a second conductivity type, different from said first conductivity type, with a channel region for the conduction of charges connecting said first region and said second region;
• said channel region, having a first portion, a second portion and a third portion;
• forming a dielectric on said channel region;
• forming a first floating gate on said dielectric, in said first trench spaced apart from said sidewall of said first trench and from said first portion of said channel region;
• said first portion of said channel region adjacent to said first region, said first floating gate for the storage of at least one of said plurality of bits;
• forming a second floating gate on said dielectric, in said second trench spaced apart from said sidewall of said second trench and from said second portion of said channel region;
• said second portion of said channel region adjacent to said second region, said second floating gate for the storage of at least another of said plurality of bits;
• forming a gate electrode on said dielectric, spaced apart from said third portion of said channel region, said third portion of said channel region between said first portion and said second portion;
• forming a first gate electrode in said first trench, said first gate electrode electrically connected to said first region and capacitively coupled to said first floating gate;
• and
• forming a second gate electrode in said second trench, said second gate electrode electrically connected to said second region and capacitively coupled to said second floating gate.

A method of manufacturing a non-volatile memory cell in a substantially single crystalline semiconductive substrate of a first conductivity type, wherein said non-volatile memory cell for storing a plurality of bits, said method comprising:

• forming a first and a second spaced apart trenches into the surface of the substrate, each of said first and second trenches having a sidewall and a bottom wall;
• forming a first region and a second region in said bottom wall of said first and second trenches, respectively, with said first region and said second region being of a second conductivity type, different from said first conductivity type, with a channel region for the conduction of charges connecting said first region and said second region;
• said channel region, having a first portion, a second portion and a third portion;
• forming a dielectric on said channel region;
• forming a first floating gate on said dielectric, in said first trench spaced apart from said sidewall of said first trench and from said first portion of said channel region;
• said first portion of said channel region adjacent to said first region, said first floating gate for the storage of at least one of said plurality of bits;
• forming a second floating gate on said dielectric, in said second trench spaced apart from said sidewall of said second trench and from said second portion of said channel region;
• said second portion of said channel region adjacent to said second region, said second floating gate for the storage of at least another of said plurality of bits;
• forming a gate electrode on said dielectric, spaced apart from said third portion of said channel region, said third portion of said channel region between said first portion and said second portion;
• forming a first gate electrode in said first trench, said first gate electrode electrically connected to said first region and capacitively coupled to said first floating gate;
• and
• forming a second gate electrode in said second trench, said second gate electrode electrically connected to said second region and capacitively coupled to said second floating gate.