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Atomic layer deposition (ALD) with HfCl4 as a precursor is widely used for HfO2 fabrication. Due to the nature of the precursor under study, i.e., HfCl4 and H2O, the presence of chlorine residues in the film due to insufficient hydrolysis is eminent. Obviously, the chlorine residue in the HfO2 film is suspected to affect the quality of the HfO2 film. In this paper, we reduced the concentration of chlorine residues by increasing the H2O oxidant pulse time in between the deposition cycles from 0.3 to 10 and 90s. Time-of-flight secondary ion mass spectrometry analysis shows that this decreases the chlorine concentration in the HfO2 film by more than one order of magnitude. However, time-dependent dielectric breakdown analysis shows that the lifetime remains quasi unaffected (within identical error bars) for the different injection cycles. Charge pumping analysis was done by varying both pulse frequency and amplitude to investigate the creation of defects, but negligible differences were observed. Therefore, we conclude that the presence of chlorine residues has no significant impact on the trap generation and reliability of ALD HfO2 layers, and this result corresponded with the mobility result. The experimental picture is confirmed with first-principle calculations that show that the presence of chlorine residues does not induce defect levels in the bandgap of HfO2. [ABSTRACT FROM AUTHOR]

In this paper, an effective technique and methodology for the estimation of fixed charge components in high-k stacks was demonstrated by varying both the SiO2 and high-k dielectric thicknesses. The SiO2 thickness was scaled on a single wafer by uniformly changing the etch time of a thermally grown SiO2 layer across the wafer. This minimized wafer-to-wafer variations and enables acquisition of statistically significant datasets. Layers with different thickness of both the nitrided and non-nitrided hafnium-silicate layers were then grown on these wafers to estimate all the interfacial and bulk charge components. The reproducibility and validity of this technique were demonstrated, and this method was used to compare the fixed charge levels in Hf-silicates (HfSiO) and nitrided-Hf-silicate (HfSiON) layers. [ABSTRACT FROM AUTHOR]

The authors demonstrate high-performing n-channel transistors with a HfO2/TaN gate stack and a low thermal-budget process using solid-phase epitaxial regrowth of the source and drain junctions. The thinnest devices have an equivalent oxide thickness (EOT) of 8 Å, a leakage current of 1.5 A/cm² at VG = 1 V, a peak mobility of 190 cm²/V · s, and a drive-current of 815 μA/μm at an OFF-state current of 0.1 μA/μm for VDD = 1.2 V. Identical gate stacks processed with a 1000-°C spike anneal have a higher peak mobility at 275 cm²/V · s, but a 5-Å higher EOT and a reduced drive current at 610 μA/μm. The observed performance improvement for the low thermal-budget devices is shown to be mostly related to the lower EOT. The time-to-breakdown measurements indicate a maximum operating voltage of 1.6 V (1.2 V at 125 °C) for a ten-year lifetime, whereas positive-bias temperature-instability :measurements indicate a sufficient lifetime for operating voltages below 0.75 V. [ABSTRACT FROM AUTHOR]

We report on a novel Au-free CMOS process-compatible process for AlGaN/GaN metal–insulator–semiconductor high-electron-mobility transistors. The process starts from a 150-mm GaN-on-Si substrate with an embedded \Si3\N4\/ \Al2\O3 bilayer gate dielectric, encapsulated by a high-temperature low-pressure chemical vapor deposited nitride layer. Power devices with a 20-mm gate width reach a maximum output current of 8 A, a breakdown voltage of 750 V, and a specific on-resistance Ron, sp of 2.9 \m\Omega\cdot\cm^2. The off-state drain leakage at 600 V is 7 \mu\A. We show robust gate dielectrics with a large gate bias swing. [ABSTRACT FROM PUBLISHER]

Very promising capacitance–voltage (C– V) characteristics of capacitors on both p- and n-type Ge substrates are demonstrated by using an in situ  \O2 plasma passivation and an \O2 ambient annealing. The capacitors exhibited a small equivalent oxide thickness of \sim1.5 nm and a low Dit \ (< \6\ast \10^11 \ \cm^-2\eV^-1) energy distribution covering the major part of the Ge bandgap (> 0.51 eV). The surface potential modulation efficiency was estimated to be \sim80% from flatband to strong inversion on both types of Ge. C–V hysteresis was less than 10 mV with positive bias up to 1.5 V. A low gate leakage current density of < \9\ast \10^-8 \ \A/cm^2 at VFB \pm \1 \ \V indicates high quality of the \HfO2/\GeO2 gate stacks. Excellent comprehensive properties suggest that a combination of \O2 plasma passivation and \O2 ambient annealing provides a promising technology for \GeO2 -based CMOS devices. [ABSTRACT FROM AUTHOR]

Cap layers have been used to modulate the effective work function (EWF) for high-k/metal-gate CMOS devices. We have investigated the impact of stacking cap layers on the EWF. Stacked cap layers consisting of two sequential cap layers, including Al2O3, Dy2O3, Sc2O3, and La2O3, were formed on HfSiON or SiON as host dielectrics. It is demonstrated that the EWF change due to the stacked cap layers corresponds to the sum of the EWF change from each single cap layer. Furthermore, no host dielectric dependence on the shifts is observed. This behavior is attributed to the complete intermixing of the stacked cap layers with the host dielectrics. [ABSTRACT FROM AUTHOR]

Conduction band-edge effective work functions (ϕm,eff) are demonstrated with TaCx and TiN by means of La2O3 capping of HfSiOx in a gate-first process flow with CMOS- compatible thermal budget. With TaCx, a 10-Å-thick La2O3 cap results in a ϕm,eff of 3.9 eV with a low equivalent oxide thickness (EOT) increase (1-2 Å) and unaffected electron mobility. With TiN, non-nitrided La2O3 capping results in a smaller ϕm,eff reduction at a larger EOT increase, while with post-cap nitridation, the TiN ϕm,eff is lower at a smaller EOT increase. Results show that the choice of metal and nitridation conditions have significant effects on La2O3 capped stacks. [ABSTRACT FROM AUTHOR]