Comparison of Different Optimization Techniques in Electron Lens Design

To design electron lens systems, applying a fully automated optimization routine has not yet been feasible, especially for the case where the optimization has many free variables of the lens system, such as all parameters that define the geometry of the lens electrodes and the voltage of each electrode. Hence, the study of the implementation of...

Tuning Parameters in the Genetic Algorithm Optimization of Electrostatic Electron Lenses

The design of electrostatic electron lenses involves the choice of many geometrical parameters for the lens electrodes as well as the choice of voltages applied to the electrodes. The purpose of the design is to focus the electrons at a specific point and to minimize the aberrations of the lens. In a previous study, genetic algorithm...

Understanding the influence of 3D sidewall roughness on observed line-edge roughness in scanning electron microscopy images

Line-edge roughness (LER) is often measured from top-down critical dimension scanning electron microscope (CD-SEM) images. The true three-dimensional roughness profile of the sidewall is typically ignored in such analyses. We study the response of a CD-SEM to sidewall roughness (SWR) by simulation. We generate random rough lines and spaces,...

Local versus Global Optimization of Electron Lens System Design

In electron optics, the design of electron lens systems is still a challenge. To optimize such systems, the objective function which should be calculated, depends on the electric potential distribution in the space created by the lenses. To obtain the electric potential, the existing methods are generally based on some mathematical techniques...

Surface effects in simulations of scanning electron microscopy images

We have investigated the contributions of surface effects to Monte Carlo simulations of top-down scanning electron microscopy (SEM) images. The elastic and inelastic scattering mechanisms in typical simulations assume that the electron is deep in the bulk of the material. In this work, we correct the inelastic model for surface effects. We...

Model improvements to simulate charging in SEM

Charging of insulators is a complex phenomenon to simulate since the accuracy of the simulations is very sensitive to the interaction of electrons with matter and electric fields. In this study, we report model improvements for a previously developed Monte-Carlo simulator to more accurately simulate samples that charge. The improvements...

Simulation of shotnoise induced side-wall roughness in electron lithography

We have developed a fast three dimensional Monte-Carlo framework for the investigation of shotnoise induced side-wall roughness (SWR) formation. The calculation outline is demonstrated by an example for an exposure of a 100nm thick layer of negative tone resist (NTR) resist on top of an infinitely thick silicon substrate. We use our home...

Pattern transfer into silicon using sub-10 nm masks made by electron beam induced deposition

To demonstrate the possibility of using EBID masks for sub-10 nm pattern transfer into silicon, first experiments were carried out by using 20-40 nm EBID masks, that were etched by different chemistries. It is experimentally verified that recipes based on hydrogen bromide, chlorine and boron trichloride can selectively etch silicon when using 20...

The effect of sidewall roughness on line edge roughness in top-down scanning electron microscopy images

Sub-10 nm structures written in ultra-thin HSQ resist layers, using Electron Beam Lithography

Isolated dots and lines with 6 nm width were written in 20 nm thick Hydrogen silsesquioxane (HSQ) layers on silicon substrates, using 100 keV electron beam lithography. The main factors that might limit the resolution, i.e. beam size, writing strategy, resist material, electron dose, development process, are discussed. We demonstrate that, by...