Calculation of multiphonon-emission assisted recombination process on extremely scaled semiconductor-insulator interface by the first principles based method

Abstract

Recently, an extremely scaled CMOS process can enable extensive and powerful computing solutions. Due to the scaled channel structure of the state-of-art device, the physical phenomena in the semiconductor-insulator interface significantly change the characteristics of the device. In particular, point defects near the interface structure act as charged trap centers. Despite the importance of proper modeling, the modeling of defects at the interface has relied on experimental data. Recently, some research has offered a parameter-free approach to evaluating the capture parameters using an atomistic interface structure via density functional theory (DFT) calculations. In particular, the multi-phonon emission (MPE) method has been used to calculate the non-radiative recombination characteristics of charged point defects in a solid. This dissertation describes a parameter-free first-principles calculation method for the semiconductor-insulator interface structure. With the building of the atomistic interface model, the supercell based defect analysis is performed for various charged states. The non-radiative capture coefficients are calculated by applying the MPE methods based on the first principle calculation result. Overall, three different interface systems are used for calculation and analysis. First, in chapter 2, we build a bulk Si structure and a crystalline Si/silicon oxide(SiO2) interface structure. With the structure building, point defects are introduced in both structures, and we analyze the defect characteristics. The electronic and vibrational properties of the atomistic structure with defects are evaluated by DFT calculation, and the capture coefficients are evaluated from the adiabatic approximation MPE method. In chapters 3 and 4, with the result of crystalline Al2O3 film deposition on β-Ga2O3 material, the atomistic β-Ga2O3/γ-Al2O3 interface structure is generated and optimized. We compare the properties evaluated from DFT calculations with the experimental values. We perform a point defect analysis with the interface structure. using intrinsic vacancy types. We then simulated a Ga2O3 power MOSFET with a vertical channel structure using the material and interfacial properties of the calculation. Chapter 5 describes how the crystalline HfO2/SiO2/Si double gate(DG) interface is generated following the channel structure of the latest FinFET or nanosheet CMOS process. Similarly, hydrogen-passivated oxygen vacancy (V_O) defects at the interface are analyzed, and the capture coefficients of the defects are evaluated by a MPE calculation method. Finally, we perform a TCAD noise simulation of a 3D nanosheet MOSFET device using the material parameters and the capture coefficients which was evaluated from the interface calculation. We further analyzed the current distribution of noise output by statistically modeling the number distribution of defects.