A combination of two complementary depth profiling techniques with sub-nm depth resolution, nuclear resonance profiling and medium energy ion scattering, and cross-sectional high-resolution transmission electron microscopy were used to study compositional and microstructural aspects of ultrathin (sub-10 nm) Al2O3 films on silicon. All three techniques demonstrate uniform continuous films of stoichiometric Al2O3 with abrupt interfaces. These film properties lead to the ability of making metal-oxide semiconductor devices with Al2O3 gate dielectric with equivalent electrical thickness in the sub-2 nm range.

Articles you may be interested inHigh capacitance density metal-insulator-metal structures based on a high-κ Hf N x O y -Si O 2 -Hf Ti O y laminate stack Appl. Phys. Lett. 92, 132902 (2008); 10.1063/1.2905273 High-temperature conduction behaviors of HfO 2 / TaN -based metal-insulator-metal capacitors J. Appl. Phys. 102, 073706 (2007); 10.1063/1.2786712 Metal-insulator-metal capacitors using atomic-layer-deposited Al 2 O 3 ∕ Hf O 2 ∕ Al 2 O 3 sandwiched dielectrics for wireless communications Physical and electrical characterization of HfO 2 metal-insulator-metal capacitors for Si analog circuit applicationsThe authors report the relationship between HfO 2 crystalline phase and the resulting electrical properties. Crystallization of amorphous HfO 2 into the monoclinic phase led to a significant increase in leakage current and formation of local defects. Admixture of 10% SiO 2 avoided formation of these defects by stabilization of the tetragonal phase, and concurrently increased the permittivity to 35. This understanding enabled fabrication of crystalline HfO 2 based metal-insulator-metal capacitors able to withstand a thermal budget of 1000°C while optimizing capacitance equivalent thickness ͑Ͻ1.3 nm͒ at low leakage ͓J͑1 V͒ Ͻ 10 −7 A/cm 2 ͔.

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A series of heterogeneous a-olefin polymerization catalysts were prepared by the immobilization of bis(butylcyclopentadienyl)zirconium dichloride, (nBuCp) 2 ZrCl 2 , on a commercial silica support (Grace 948) using different procedures. The preparation parameters, namely, silica activation temperature, grafting temperature, grafting time, and solvent, were evaluated in terms of metal content on silica and ethylene homopolymerization activity. Metal contents were determined by Rutherford back-scattering spectrometry (RBS). In the temperature activation range between 373 and 723 K, silica surface saturation in Zr was found to be around 0.34 wt.-% Zr/SiO 2 . However, polymer polydispersity is shown to decrease with increasing support activation temperature. A better control in the generation of the active surface species was achieved with thermal pretreatment temperatures close to 723 K. The grafting reaction was seen to be immediate. Longer grafting times or higher temperatures bore deactivated species. Practically all the systems were active in ethylene polymerization in the presence of MAO, but the highest yield was obtained after grafting at 353 K for 1 h in toluene solution, employing silica pretreated at 723 K.

We demonstrate, for the first time, a HfLaSiON/metal gate stack that concurrently achieves the following: low threshold voltage (V T =0.33V), low equivalent oxide thickness (EOT=0.91nm) (T inv =1.3nm) and 83% SiO 2 mobility. Key enablers of this result are 1) La doped HfSiON for n-FET V T tuning 2) HfO 2 :SiO 2 alloy ratio with 10% SiO 2 suppressing crystallization up to 1070°C, 3) interlayer SiO 2 (IL) to reduced bias temperature instability (BTI) and 4) plasma nitridation (N*)/post nitridation anneal (PNA) sequence for EOT scaling. This work advances high-k/band edge metal gate (MG) efforts by showing scalability of HfLaSiON to EOT=0.91nm without mobility or BTI tradeoff, while matching the V T of a SiO 2 /n-PolySi control.