Simulation of SOI-like kink effects in a ´horseshoe-drain´ MOSFET for 16M and 64M DRAM applications

The MOSFET structure of a scaled SCC trench cell with a buried drain has been studied using MINIMOS. In this cell the depletion regions surrounding the buried drain can pinch off the substrate, causing sharply increased avalanche carrier generation similar to, but more severe than, the kink effect in SOI MOSFETs. The mechanism for the enhanced avalanche generation and its dependence on bias conditions and geometry have been studied, and simple design rules for punchth-rough and pinchoff by the buried drain have been established.