Thin box metal backgate extremely thin SOI device

摘要

SOI structures with silicon layers less than 20 nm thick are used to form ETSOI semiconductor devices. ETSOI devices are manufactured using a thin tungsten backgate encapsulated by thin nitride layers to prevent metal oxidation, the tungsten backgate being characterized by its low resistivity. The structure includes at least one FET having a gate stack formed by a high-K metal gate and a tungsten region superimposed thereon, the footprint of the gate stack utilizing the thin SOI layer as a channel. The SOI structure thus formed controls the Vt variation from the thin SOI thickness and dopants therein. The ETSOI high-K metal backgate fully depleted device in conjunction with the thin BOX provides an excellent short channel control and lowers the drain induced bias and sub-threshold swings. The structure supports the evidence of the stability of the wafer having a tungsten film during thermal processing, during STI and contact formation.