Lattice Structure And Thermal Properties Of High-ε Hf_1-xSi_xO₂

In the1960s, Dr Gordon Moore proposed the famous Moore’s Law, that is, the size ofintegrated circuits decreases0.7times every three years, and the level of integration increasesfour times every three years. The development speed of integrated circuits industry hasfollowed the Moore’s Law for about40years. The size of CMOS devices has decreased sincethen, and the level of integration has increased. The thickness of silicon dioxide gate which ismedium layer. But due to the effect caused by quantum tunneling effect, the increase ofleakage current index will affect the performance of traditional devices very badlly. With theupgrade of semiconductor integrated circuit manufacturing process, when the thickness ofsilicon dioxide decreased to nanoscale, electron would pass through medium layer as a resultof quantum tunneling effect, which would cause the layer invalid. In order to solve thisproblem, high-e material is used as a substitution of silicon dioxide to form medium layer,which would increase the physical thickness of medium layer without increasing theequivalent thickness. This method could minimize the leakage current index and impuritydiffusion, and inhibit the quantum tunneling effect. If high-e material wants to replacesilicon dioxide, it not only needs to have the similar crystal structure and electronic propertiesas SiO₂/Si has, but to be compatible with current semiconductor manufacturing process.Among many substitutions, HfO₂raised much attention as its high dielectric constant （about25）, wide interbank gap （about5.68eV） and its high thermal stability with Si. Currently,HfO₂is considered as the very potential high-k material to replace SiO₂.Due to the present integrated circuit is still Si substrate, considering High-e materialand Si lattice matched to take into account and process compatible, this paper intend to useatomistic simulation techniques to examine the SiO₂-based High-e materials （HfO₂/SiO₂）.Study found that the material information at the atomic level is still relatively lack, Atomisticsimulation method is fast, we will examine the material’s atomic distribution in the latticedimensions at the atomic level detail, the local lattice structure and their thermal properties.Classical atomistic simulations based on Born core-shell model were performed tosystematically study the crystal structure and thermal properties of Hf_1-xSixO₂, This papercalculate thermal properties such as lattice constants, bond lengths and angles, the elasticmodulus, the coefficient of thermal expansion, specific heat, Grüneisen parameter, phonondensity of states, and Debye temperature and HfO₂surface at high temperature, as differenttemperatures and different Si-doping concentrations. It is found that the lattice constantincreases. Both the specific heat of constant volume and the coefficient of thermal expansionof Hf_1-xSixO₂reduce with the increasing of Si-doping concentrations. Some simulation resultscorrespond with experimental data, and we anticipate our results will be helpful to understandlattice structure and thermal properties of Hf_1-xSixO₂and select the bases on which Hf_1-xSixO₂ materials are prepared.