Thin-box metal backgate extremely thin soi device

Abstract

Silicon-on-insulator (SOI) structures with silicon layers less than 20 nm thick are used to form extremely thin silicon-on-insulator (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 further 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 significantly lowers the drain induced bias and sub-threshold swings. The present structure supports the evidence of the stability of the wafer having a tungsten film during thermal processing, and especially during STI and contact formation.