Modeling of Dopant Activation in Germanium

Nonplanar field effect transistors (FET) such as FinFETs have been the major devices in advanced integrated circuits. The small cross-sectional area of such devices can suppress short channel effects. However, the series resistance of the device structure is high and the operation speed of FETs is therefore reduced. Materials with high carrier mobility are considered to improve the device performance. Germanium has been the best candidate to replace silicon because of its high electron and hole mobility. It is known that n-type dopants in germanium suffer from low activation. This affects the application of germanium transistors. This project will develop models for dopant activation in germanium. In the first year, a platform to analyze dopant activation will be established by integrating the novel back-side Hall measurement (BHM) with differential Hall measurement (DHM) to reveal the reactions between dopants and defects in the early stage of annealing. Simulation will be performed to optimize the test structures for BHM. The depth profiles of active dopants obtained using DHM will also be calibrated. Multiple implantation and multiple annealing (MIMA) will be performed in the second year. High-dose implantation for surface preamorphization will be performed as well. The change of the depth profiles of active dopants and electrically active defects during heat treatments can be obtained using the activation analysis platform of BHM and DHM. Therefore, we can understand the physical mechanism of interactions between dopants and defects. Dopant activation models can be generated according to the physical mechanisms. Atomistic kinetic Monde-Carlo (KMC) simulation will be performed to reveal microscopic reactions of dopants and defects. Continuum equation models will be established based on macroscopic dopant activation behaviors so that it can be integrated with conventional process simulation platform. The results of this study will help us to understand the electrically active defects in germanium. Consequently, the performance of integrated circuits can be improved by mass production of germanium transistors.

Project ID:PB10507-1734
External Project ID:MOST105-2221-E182-061