Gate last MOSFET with air spacer and self-aligned contacts for dense memories

Gate-last metal-gate/high-k technology will allow MOSFET scaling to unprecedented levels. When the gate length is small, the dominant capacitance in the MOSFET is the gate to contact-plug capacitance. This is especially so with SAC (self-aligned contact) technology popular with high density memories. This papers proposes a compact SAC gate-last air-spacer structure that yield small size, high speed, and low switching energy. The improvement over the conventional SAC device increases dramatically with scaling.