Selective etch process for fab-compatible top contacts, replacement oxide, and interlayer removal in 2D FETs

Abstract

Two rarely used features of Transition Metal Dichalcogenides (TMDs) are their exceptional chemical stability in some wet etchants and their unique anisotropic van der Waals structure. These are leveraged to selectively recess the oxide cap, and fabricate 2D FETs with damascene-type top contacts on monolayer WS2, MoS2, and multilayer WSe2 in a 300mm pilot line. In addition, the process is extended to a replacement oxide stack, and interlayer selective removal is demonstrated using liquid intercalation, reducing the top gate CET from 2.5 to 1.5nm. These form three new fundamental building blocks for 2D integration technology.