Simulation study of surface sputtering and distribution of ions in silicon due to low-energy high-fluence cobalt irradiation

The study of the range and distribution of low-energy heavy ions implanted into lighter substrates is paramount important in terms of three-dimensional device fabrications. In this study, we report the re-distribution of implanted ions due to the sputtering of target atoms, simulated considering dynamic changes in the target due to the high-fluence irradiation of Co and Fe ions at low energy (55 keV) in Silicon substrate and nanowires. The simulations were compared by using various ion-solid interaction codes that are capable of incorporating the targets with both one-dimensional (1D) and three-dimensional (3D) structures. In the 1D simulation codes, the target is generally defined as a stack of sharp interfaced layers that have an infinite lateral extension. Both static code like Stopping and Range of Ions in Matter (SRIM) and dynamic code like Static and Dynamic Trim for Sequential and Parallel computer (SDTrimSP) were utilized to carry out the simulations in silicon substrates. However, to simulate the distribution of ions with target layers involving nanostructures with a curved surface such as nanowires Ion range and damage in nanostructures (Iradina) code was used. Silicon nanowires of different diameters were chosen as the target, and Co ions were implanted at single energy along the surface normal. The fluence of the Co ions was then varied to obtain the optimal distribution of implanted ions in the silicon nanowire. The Si nanowire shows a curved depth profile for the implanted ions with different ranges towards the edge and the center of the nanowire. The surface sputtering in the case of the nanowire was more as compared to the bulk Si substrate. However, in the case of the Si substrate, the atoms are found preferentially sputtered in the forward direction between 30 degrees - 60 degrees angle with a peak around 45 degrees angle to the target surface normal with variation in the angle of incidence.

Automated summary

This study investigates the redistribution of implanted ions in silicon substrates and nanowires under low-energy Co and Fe ion irradiation through simulations. The results show that the curved depth profile of silicon nanowires influences the distribution of implanted ions, with more surface sputtering observed in nanowires compared to bulk silicon substrates.