Memory cell with reduced DIBL and Vss resistance
View Patent ↗According to one exemplary embodiment, a method for fabricating a floating gate memory cell on substrate comprises a step of forming a spacer adjacent to a source sidewall of a stacked gate structure, where the stacked gate structure is situated over a channel region in substrate. The method further comprises forming a high energy implant doped region adjacent to the spacer in the source region of substrate. The method further comprises forming a recess in a source region of the substrate, where the recess has a sidewall, a bottom, and a depth, and where the sidewall of the recess is situated adjacent to a source of the floating gate memory cell. According to this exemplary embodiment, the spacer causes the source to have a reduced lateral straggle and diffusion in the channel region, which causes a reduction in drain induced barrier lowering (DIBL) in the floating gate memory cell.
1. A floating gate memory cell situated on a substrate, said floating gate memory cell comprising:
a stacked gate structure situated on said substrate, said stacked gate structure being situated over a channel region in said substrate;
a recess formed in said substrate adjacent to said stacked gate structure, said recess having a sloped sidewall, a bottom, and a depth;
a source of said floating gate memory cell situated adjacent to said sloped sidewall of said recess and under said stacked gate structure;
a spacer situated adjacent to said stacked gate structure and adjacent to said sloped sidewall of said recess, said spacer extending to said bottom of said recess;
a mask situated over a drain side of said stacked gate structure and over a drain region of said floating gate memory cell, wherein said mask is not situated over said recess;
wherein said spacer causes said source to have a reduced lateral straggle and diffusion in said channel region.
2. The floating gate memory cell of claim 1 further comprising a Vss connection region situated under said bottom of said recess and under said source, said Vss connection region being connected to said source.
3. The floating gate memory cell of claim 1 wherein said sloped sidewall of said recess forms an angle of between approximately 85.0 degrees and approximately 89.0 degrees with a top surface of said substrate.
4. The floating gate memory cell of claim 1 wherein said reduced lateral straggle and diffusion of said source causes a reduction in drain induced barrier lowering in said floating gate memory cell.
5. The floating gate memory cell of claim 1 wherein said depth of said recess is between approximately 100.0 Angstroms and approximately 500.0 Angstroms.