MULTI-GATE FIELD-EFFECT TRANSISTORS WITH VARIABLE FIN HEIGHTS

摘要

Multi-gate devices and methods of their fabrication are disclosed. A multi-gate device can include a gate structure and a plurality of fins. The gate structure envelops a plurality of surfaces of the fins, which are directly on a substrate that is composed of a semiconducting material. Each of the fins provides a channel between a respective source and a respective drain, is composed of the semiconducting material and is doped. A first fin of the plurality of fins has a first height that is different from a second height of a second fin of the plurality of fins such that drive currents of the first and second fins are different. Further, the first and second fins form a respective cohesive structure of the semiconducting material with the substrate. In addition, surfaces of the substrate that border the fins are disposed at a same vertical position.