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NIST Simulation of E-beam Inspection and CD-SEM in-line metrology: Interim Report for 1st year of project



John S. Villarrubia


This report summarizes results from the first year of a 2-year project to develop a simulator for electron beam (e-beam) inspection and critical dimension-scanning electron microscope (CD-SEM) inline metrology tools. The goal is to improve on previous simulators and develop a tool that can be used to explore the fundamental limits of e-beam instruments for imaging and measuring small features. Initial work included improving the secondary electron generation model, assembling a database of the material properties and computing scattering tables with which to use the improved model, and improving the simulation algorithms for non-conducting materials. Work planned for the second year of the project will develop the capability to model the charge distribution in non-conducting samples and explore SEM capabilities for inspecting and measuring at sub-30 nm technology nodes. The JMONSEL simulation models have been improved as follows: 1. Three new options for elastic scattering have been added. One of these determines the relevant cross sections by interpolating NIST Electron Elastic-Scattering Cross-section Database (SRD 64). 2. The method of calculating scattering tables for the dielectric function theory (DFT) secondary electron (SE) generation model has been generalized to include semiconductors and insulators. 3. The required energy loss function (ELF) input data for scattering table calculations have been collected for 40 elemental solids and 17 compounds. The source of many of these was the same input data used for contributions to the NIST Electron Inelastic-Mean-Free-Path Database (SRD 71). 4. Scattering tables have been computed for 17 materials. 5. A backup SE generation model has been written. The backup model has different and generally less stringent prerequisites than the DFT model. Many materials for which the requisite ELF data are unavailable can be simulated using the backup model instead. 6. An interface scattering model allows the potential


critical dimension (CD), defect detection, Monte Carlo modeling, scanning electron microscopy (SEM)


Villarrubia, J. (2010), NIST Simulation of E-beam Inspection and CD-SEM in-line metrology: Interim Report for 1st year of project, ISMI, [online], (Accessed June 16, 2024)


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Created March 1, 2010, Updated February 19, 2017