Eeprom cell with self-aligned tunneling window
AssigneeLattice Semiconductor Corporation
InventorsXIAO YU LI, SUNIL D. MEHTA, CHRISTOPHER O. SCHMIDT
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Abstract
An improved EEPROM cell with a self-aligned tunneling window is provided which is fabricated by a standard STI process so as to produce a smaller layout size and a reduced cell height. The EEPROM cell includes a floating gate, a programmable junction region, and a tunneling oxide layer separating the programmable junction region and the floating gate. The length dimension of the floating gate is less than the length dimension of the tunneling window so that the tunneling window is overlapping the floating gate. The tunneling window is self-aligned by edges forming the length dimension of the floating gate so as to form a self-aligned tunneling window.
Claims8
In an EEPROM cell including a floating gate, a programmable junction region, and a tunneling oxide layer separating said programmable junction region and said floating gate, said tunneling oxide layer defining a tunneling window which allows for programming and erasing of said floating gate by tunneling electrons therethrough, wherein the improvement comprising:
- said programmable junction region having a width dimension and length dimension so as to define a first area;
- said tunneling window having a width dimension and a length dimension so as to define a second area;
- said floating gate having a width dimension and a length dimension so as to define a third area;
- said width dimension of said tunneling window being greater than said width dimension of said programmable junction region so as to overlap said programmable junction region;
- said length dimension of said tunneling window being less than said length dimension of said programmable junction region so as to be confined within the length dimension of said programmable junction region;
- said length dimension of said floating gate being less than said length dimension of said tunneling window so that said tunneling window is overlapping said floating gate;
- and
- said width dimension of said floating gate being larger than said width dimension of said tunneling window so that said floating gate is overlapping said tunneling window,
- whereby said tunneling window is self-aligned by edges formed said length dimension of said floating gate so as to form a self-aligned tunneling window.
Dependencies are inferred from the claim text.