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GdxHf1-xOy. thin films were deposited by atomic layer deposition (ALD) using tris(isopropyl-cyclopentadienyl) gadolinium [Gd(PrCp)3] and HfCI4 in combination with H2O as an oxidizer. Growth curves showed a nearly ideal ALD behavior. The growth per individual Gd(iPrCp)3/H2O or HfCI4/H2O cycle was 0.55 A, independent of the Gd/(Gd + Hf) composition x in the studied range. This indicates that the amount of HfO2 deposited during a HfCI4/H2O cycle was essentially identical to the amount of Gd2O3 deposited during a Gd(iPrCp)3/H2O cycle, assuming identical atomic densities of the films independent of composition. The crystallization of GdxHf1-xOy with Gd/(Gd + Hf) contents x between 7 and 30% was studied. Films with x ⩾10% crystallized into a cubic/tetragonal HfO2-like phase during spike or laser annealing up to 1300°C, demonstrating that the cubic/tetragonal phase is thermally stable in this temperature range. A maximum dielectric constant of K∼ 36 was found for a Gd/(Gd + Hf) concentration of x 11%. [ABSTRACT FROM AUTHOR]

Although the next generation high-k gate dielectrics has been defined for the 45 nm complementary metal oxide semiconductor technology node, threshold voltage control and equivalent oxide thickness (EOT) scaling remain concerns for future devices. Therefore, the authors explored the effect of incorporating dysprosium in the gate stack. Results suggest that improved EOT-leakage scaling is possible by adding Dy to the interfacial SiO2 layer in a 1:1 ratio or by adding 10% Dy to bulk HfO2. The deposition of a 1 nm Dy2O3 cap layer lowered the threshold voltage by ∼250 mV. In addition, for future dynamic random access memory capacitor applications, dielectrics with [variant_greek_epsilon] of 50–130 are projected by the International Technology Roadmap for Semiconductors, unachievable with standard high-k dielectrics. Theoretical modeling can help direct the experimental work needed for extensive screening of alternative dielectrics. Moreover, materials such as perovskites only exhibit a sufficiently high-k value when properly crystallized. Therefore, control over the crystalline phase of the material might become a necessity to obtain the proper material characteristics as shown for SrTiOx. After crystallization, the permittivity was observed to increase from 20 to 135. In addition, material and gate stack optimization to limit leakage current densities for these higher-k dielectrics will be needed. [ABSTRACT FROM AUTHOR]

Abstract: A first-principles Density Functional Theory (DFT) approach was employed to predict the effective charges, phonon modes, band-gap and dielectric constant of a series of Sr-rich SrTiO3. The fabricated MIM capacitors confirm the theoretical trends obtained for the dielectric constants, the later showing a possible upper limit of the dielectric response. [Copyright &y& Elsevier]