Disclosed herein is a DRAM memory cell featuring a reduced size, increased
retention time, and compatibility with standard logic manufacturing
processes, making it well-suited for use as embedded DRAM. The memory
cell disclosed herein includes a pass-gate transistor and a storage
region. The transistor includes a gate and a drain. The storage region
includes a trench, which is preferably a Shallow Trench Isolation (STI).
A non-insulating structure, e.g., formed of polysilicon or metal, is
located in the trench as serves as a capacitor node. The trench is
partially defined by a doped sidewall that serves as a source for the
transistor. The poly structure and the trench sidewall are separated by a
dielectric layer. The write operation involves charge transport to the
non-insulating structure by direct tunneling through the dielectric
layer. The read operation is assisted by Gate Induced Drain Leakage
(GIDL) current generated on the surface of the sidewall.