A general consideration of incident impact energy accumulation in molecular dynamics thin film simulations—a new approach using thermal control layer marching algorithms

Abstract

This paper investigates several highly accurate algorithms which can be used to calculate the morphology in a wide range of thin film process simulations, and which require minimum computational effort. Three different algorithms are considered, namely the kinetic energy corrector (KEC) algorithm, the thermal control layer marching (TLM) algorithm, and the thermal control layer marching algorithm with an incorporated KEC function (TLMC). A common characteristic of these algorithms is that they all address the recovery of the impact incident energy within the free reaction layer. However, they differ in their treatment of the thermal control layer. The TLM and TLMC algorithms consider this layer to be moveable, whereas the KEC algorithm regards it as being fixed. The advantage of employing a moveable thermal control layer is that the computational effort required to carry out simulation is reduced since the atoms lying below this layer are excluded. The relative accuracy and efficiency of the proposed algorithms are evaluated by considering their use in the simulation of the trench-filling problem associated with the damascene process. The results of the present investigation indicate that the TLM algorithm has the ability to provide an accurate morphology calculation for low and medium energy incident atoms. However, for higher incident energy impacts, the TLMC algorithm is found to be a more appropriate choice because the incorporated energy corrector function is required to remove the higher energy accumulation which occurs within the deposited atoms. Furthermore, for all three algorithms, it is noted that a suitable specification of the free reaction layer thickness is essential in determining the accuracy and efficiency of the simulation. Finally, this paper discusses the relationship between the energy absorption rate and the thickness of the free reaction layer, and presents the optimal free reaction layer thickness for different incident energy intensities.