Chemical Bonding, Interfaces, and Defects in Hafnium Oxide∕Germanium Oxynitride Gate Stacks on Ge(100)

Abstract

Correlations among interface properties and chemical bonding characteristics in HfnormalO2∕GenormalOxnormalNy∕Ge metal–insulator–semiconductor stacks were investigated using in situ remote nitridation of the Ge(100) surface prior to HfnormalO2 atomic layer deposition. Ultrathin (∼1.1nm) , thermally stable, and aqueous etch-resistant GenormalOxnormalNy interface layers that exhibited Ge core-level photoelectron spectra similar to stoichiometric normalGe3normalN4 were synthesized. To evaluate GenormalOxnormalNy∕Ge interface defects, the density of interface states (Dit) was extracted by the conductance method across the bandgap. Forming gas annealed (FGA) samples exhibited substantially lower Dit (∼1×1012cm−2eV−1) than did high-vacuum-annealed and inert gas anneal samples (∼1×1013cm−2eV−1) . Germanium core-level photoelectron spectra from similar FGA-treated samples detected out-diffusion of germanium oxide to the HfnormalO2 film surface and apparent modification of chemical bonding at the GenormalOxnormalNy∕Ge interface which is related to the reduced Dit .

Effects of post-deposition annealing ambient on Y2O3 gate deposited on silicon by RF magnetron sputtering

“…It had been reported that the presence of N 2 was capable of performing nitridation. Besides, H 2 present in FG ambient was also efficient in occupying O 2 related defects in the Y 2 O 3 films [58] as well as passivating the oxidesemiconductor interface defects (P bx ) [59,60]. The passivation of P bx by H 2 was represented by the following equation [61,62]:…”

Hafnium oxide/germanium oxynitride gate stacks on germanium: Capacitance scaling and interface state density

“…Therefore, a H 2 / N 2 / Ar gas mixture was used for nitridation ͑details described elsewhere͒. 5 Electrical properties were evaluated using MOS capacitors with HfO 2 gate dielectric layers deposited at 225°C using tetradimethylaminohafnium ͑TDMAHf, Air Liquide͒ and H 2 O by ALD for 25-75 cycles ͑3-6 nm͒ after in situ Ge substrate nitridation in the ALD chamber ͑no vacuum break͒. Pt gate electrodes were deposited by electron beam evaporation through a shadow mask, followed by a forming gas anneal ͑FGA͒ ͑H 2 :Ar=5:100͒ at 370°C for 30 min.…”

“…Based on the Ge 3 N 4 -like XPS features observed from the as-grown layer, oxygen is considered to be incorporated in the GeO x N y layer during the subsequent HfO 2 ALD process, which is performed without an intervening vacuum break. 5 The thickness and N/GeON ratios were calculated 5 a͒ Electronic mail: yasuhiro.oshima@us.tel.com. from the ex situ Ge 3d XPS spectra shown in Fig.…”

Effect of Annealing Ambient on Structural and Electrical Properties of Ge Metal-Oxide-Semiconductor Capacitors with Pt Gate Electrode and HfO<SUB>2</SUB> Gate Dielectric

“…Chen et al 13) described degraded electrical properties on Ge substrates with different high-k gate dielectrics such as HfO 2 and Al 2 O 3 without an intentional IL after annealing in a forming gas (FG) ambient at $500 C, due to direct contact between the high-k material and the Ge. Oshima et al 14) observed higher leakage currents in FGannealed devices at 370 C than in as-grown devices when HfO 2 was deposited directly on a chemically cleaned Ge substrate. Cheng et al 15) experimentally observed that the out-diffusion of Ge during thermal treatment in NH 3 ambient led to degraded leakage current characteristics.…”