Effect of Yttrium Treatment on Germanium-Oxide-Based Interfacial Layer of Ge P-Channel Metal-Oxide-Semiconductor Field-Effect Transistor Fabricated Through in Situ Plasma-Enhanced Atomic Layer Deposition

This study investigated the effect of yttrium (Y) treatment on a germanium (Ge)-oxide-based interfacial layer (IL) through in situ plasma-enhanced atomic layer deposition (PEALD). Time-of-flight secondary-ion mass spectrometry revealed that the surface reaction and deposition could be successfully performed with a Y precursor, and X-ray photoelectron spectroscopy (XPS) revealed that Y treatment on an IL can suppress GeOx volatilization. A metal-oxide-semiconductor capacitor gate-stack with a Y-GeOx IL has a low leakage current density (2.1× 10-5 A/cm2) and a low interface trap density (approximately 5.5× 1011 eV-1 cm-2) under optimized temperatures. Moreover, the Ge P-channel metal-oxide-semiconductor field-effect transistor (P-MOSFET) containing a gate-stack with a Y-treated Ge-oxide-based IL exhibited a high ION/IOFF ratio and low OFF-state current. Therefore, applying the proposed Y treatment on the IL of a Ge P-MOSFET can help achieve a subnanometer equivalent oxide thickness (EOT) and an extremely low gate leakage current.