Interface Chemistry and Dielectric Optimization of TMA-Passivated high-k/Ge Gate Stacks by ALD-Driven Laminated Interlayers.

In the present study, a comparative study on the influence of different laminated stacks driven by aomic layer deposition (ALD) on the interfacial and electrcial properties of high-k/Ge gate stacks passivated by trimethylaluminum (TMA) has been performed in detail via X-ray photoelectron spectroscopy (XPS) and electrical measurements. XPS measurements indicate that HfO2/Al2O3/Ge gate stacks can effectively inhibit the formation of Ge suboxides and a low-k germanate layer. Compared to Al2O3/HfO2 and HfO2/Al2O3/HfO2 gate stacks, the HfO2/Al2O3/Ge metal oxide semiconductor (MOS) capacitors exhibited improved electrical performance, including a maximum permittivity of 18.15, disappearing hysteresis, an almost neglected flat band voltage of 0.01 V, and a minimum leakage current density of 3.82 × 10-8 A/cm2 at room temperature. Especially, the leakage current mechanisms of Ge-MOS capacitors based on different laminated stacks measured at room temperature and low temperature (77-327 K) have been comprehensively analyzed. By comparing three different laminated gate stacks, it can be inferred that HfO2/Al2O3/Ge gate stacks have a potential application prospect in Ge-based microelectronic devices.