$\hbox{n}^{+}/\hbox{p}^{+}$ Gate Bulk FinFETs With Locally Separated Channel Structure for Sub-50-nm DRAM Cell Transistors

We proposed a new p
⁺
/n
⁺
poly-Si gate bulk fin-type field-effect transistor that has two channel fins separated locally by a shallow trench filled with oxide or p
⁺
polygate. Key device characteristics were investigated by changing the n
⁺
poly-Si gate length La, the material filling the trench, and the width and length of the trench at a given gate length L
_g
. It was shown that the trench filled with p
⁺
poly-Si gate should not be contacted with the source/drain diffusion region to achieve an excellent I
_on
/I
_off
(> 1010) that is suitable for sub-50-nm dynamic random access memory cell transistors. Based on the aforementioned device structure, we designed reasonable Ls/Lg and channel fin width W
_cfin
at given L
_g
's of 30, 40, and 50 nm.