Level set approach for the simulation of focused ion beam processing on the micro/nano scale

Abstract

The level set method, introduced by Osher and Sethian (1988 J. Comput. Phys. 79 12-49), has recently become popular in the simulation of etching, deposition and photolithography processes in semiconductor manufacturing, as it is a highly robust and accurate computational technique for tracking moving interfaces. In this paper, the level set approach is applied to focused ion beam fabrication, allowing for the first time the simulation of targets with sub-regions that change their connectivity during processing. It is implemented in the code AMADEUS-level set (advanced modelling and design environment for sputter processes), which is capable of simulating surface topography changes in two dimensions taking re-deposition fluxes into account. We present two examples of comparisons between simulation and experiment that demonstrate the predictive capability of the code.

Continuum modeling of particle redeposition during ion-beam erosion

“…While redeposition has been investigated in detail in the field of focused ion-beam milling [44][45][46][47][48], its impact on the self-organized pattern formation during ion-beam erosion has been controversially discussed: Anspach and Linz concluded based on the results of a discrete solid-onsolid model that redeposition shares substantial properties with the damping term [49]. For a more exact model, however, one has to incorporate higher order terms, in particular a quadratic damping term c(H −H) 2 , and the coefficients depend on the aspect ratio of the morphology [50].…”

Practical Surface Sculpting Method for the Fabrication of Predefined Curved Structures using Focused Ion Beam

“…The simulation method and related model are exactly described in the literature [25][26][27]. In the simulation, the ion dose profiles are used as input; the final simulation results should be similar to the desired shape if the SSDM is suitable for the fabrication of predefined features.…”

Three-dimensional simulation of focused ion beam processing using the level set method

“…The ion beam is usually approximated to be collimated and its profile is considered to be Gaussian [3], [5], [7]. Hence, the ion flux density F obeys…”

“…Realistic simulations also require the incorporation of redeposition effects [5]- [7], [10]. Sputtered particles are able to stick to any other reachable parts of the surface.…”

“…The only three-dimensional approach we are aware of, uses a segmentbased method for surface tracking [7], which is not able to describe any topological changes of the surface. An improved approach is based on the level set (LS) method [8], which has already been successfully applied to two-dimensional FIB simulations [5]. This paper demonstrates the application of the LS method in three dimensions by means of a typical FIB process model.…”