Effect of H₂S pre-annealing treatment on interfacial and electrical properties of HfO₂/Si_1−xGe_x (x = 0–0.3)

Abstract

To understand the effect of H2S pre-annealing treatment on a Si1−xGex alloy film, the interfacial and electrical characteristics of atomic-layer-deposited HfO2/Si1−xGex were studied while varying the Ge concentration (x value) from 0 to 0.3.

Electrical Properties of HfO2 on Si1–xGex Substrates Pretreated Using a Y Precursor with and without Subsequent Oxidant Pulsing

“…7,10 Figure 3 compares the D it values at the trap energy level of 0.4 eV above the valence band edge, which was extracted using a conductance method with a procedure identical to that employed in previous studies. 8,25 Regardless of the interfacial pretreatment methods, the D it values increase by more than 1 or 2 orders of magnitude with increasing Ge concentration of the substrate, which is owing to the increased formation of undesired GeO x at the HfO 2 /Si 1−x Ge x interface. As expected from the C−V curves in Figure 1, both the YT1 (w/H 2 O) and YT2 (w/o H 2 O) pretreatments effectively reduce the D it values for the Si 0.85 Ge 0.15 and Si 0.7 Ge 0.3 samples, demonstrating that the two pretreatments are effective in restraining the formation of Ge dangling bonds, similar to the results of a previous study that used a pure Ge substrate.…”

“…As observed in Figure , an increase in the Ge concentration of the Si 1– x Ge x substrates causes a large frequency dispersion of the C – V curves due to the high density of interface states located near the lower half of the Si 1– x Ge x band gap. These interface states are closely associated with the Ge dangling bonds formed by the thermodynamically unstable GeO x at the interfacial region. , Figure compares the D it values at the trap energy level of 0.4 eV above the valence band edge, which was extracted using a conductance method with a procedure identical to that employed in previous studies. , Regardless of the interfacial pretreatment methods, the D it values increase by more than 1 or 2 orders of magnitude with increasing Ge concentration of the substrate, which is owing to the increased formation of undesired GeO x at the HfO 2 /Si 1– x Ge x interface. As expected from the C – V curves in Figure , both the YT1 (w/H 2 O) and YT2 (w/o H 2 O) pretreatments effectively reduce the D it values for the Si 0.85 Ge 0.15 and Si 0.7 Ge 0.3 samples, demonstrating that the two pretreatments are effective in restraining the formation of Ge dangling bonds, similar to the results of a previous study that used a pure Ge substrate .…”

“…The mixing of single-crystalline Si channels with Ge has been extensively employed as the most practical and promising method of increasing the carrier mobility of high-performance metal–oxide–semiconductor field-effect transistors (MOSFETs) . Owing to the complete compatibility of epitaxial Si 1– x Ge x films with recent Si device integration processes, these films can be easily employed even for the most recent gate-all-around MOSFETs with sub-3 nm technology nodes. − Moreover, HfO 2 -based films have been extensively studied as a high- k gate dielectric film because of their excellent thermal stability and relatively high dielectric constant. − However, the most critical problem hindering the practical use of Si 1– x Ge x films is their Si 1– x Ge x /high- k gate dielectric interfacial characteristics, which must be improved to a level similar to that of the conventional high- k /Si interface. The poor electrical characteristics of high- k /Si 1– x Ge x films are believed to stem from the formation of thermodynamically unstable Ge sub oxides (GeO x ) at the high- k /Si 1– x Ge x interface. ,,, …”