In this work, we present experimental results examining the energy distribution of the relatively high ͑Ͼ1 ϫ 10 11 cm −2 ͒ electrically active interface defects which are commonly observed in high-dielectric-constant ͑high-k͒ metal-insulator-silicon systems during high-k process development. This paper extends previous studies on the Si͑100͒/SiO x /HfO 2 system to include a comparative analysis of the density and energy distribution of interface defects for HfO 2 , lanthanum silicate ͑LaSiO x ͒, and Gd 2 O 3 thin films on ͑100͒ orientation silicon formed by a range of deposition techniques. The analysis of the interface defect density across the energy gap, for samples which experience no H 2 /N 2 annealing following the gate stack formation, reveals a peak density ͑ϳ2 ϫ 10 12 cm −2 eV −1 to ϳ1 ϫ 10 13 cm −2 eV −1 ͒ at 0.83-0.92 eV above the silicon valence bandedge for the HfO 2 , LaSiO x , and Gd 2 O 3 thin films on Si͑100͒. The characteristic peak in the interface state density ͑0.83-0.92 eV͒ is obtained for samples where no interface silicon oxide layer is observed from transmission electron microscopy. Analysis suggests silicon dangling bond ͑ P bo ͒ centers as the common origin for the dominant interface defects for the various Si͑100͒/SiO x /high-k/metal gate systems. The results of forming gas ͑H 2 /N 2 ͒ annealing over the temperature range 350-555°C are presented and indicate interface state density reduction, as expected for silicon dangling bond centers. The technological relevance of the results is discussed.
We investigate the impact of rapid thermal anneals on structural and electrical properties of crystalline Gd 2 O 3 layers grown on Si with different orientations. Due to additional oxygen from the annealing ambient, a structureless two-layer stack (silicon-oxide-like and silicate-like) between the silicon and the crystalline oxide will be formed. The degradation of layers can be significantly reduced by sealing the layer with a-Si prior to annealing. For the capped layers, the effective capacitance equivalent thickness increases only slightly even after a 1000 • C anneal.
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