Very Low-Work-Function ALD-Erbium Carbide (ErC₂) Metal Electrode on High-<inline-formula> <tex-math notation="LaTeX">$K$ </tex-math> </inline-formula> Dielectrics

Abstract

Erbium carbide (ErC <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) prepared by atomic layer deposition (ALD) is successfully demonstrated for the first time as a novel work function (WF) metal for nMOSFET applications. The prepared ErC <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> shows a very low effective WF (eWF), as low as 3.9 eV on HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , yet with excellent thermal stability. In addition, it did not show significant Fermi-level pinning on high-k dielectrics even after high-temperature annealing. The low eWF property of ErC <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> originates from the properties of the lanthanide family, while its good thermal stability is attributed to the properties of metal carbides. ALD-ErC <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> has superior conformality over other deposition methods, and thus is a strong candidate for 3-D structure devices.