SEM Monitor is a diagnostic tool known as "Sharpness Analysis," used to evaluate SEM-based metrology systems. The analysis capability was developed for use for on-line instrument diagnostic and tool matching in a production environment as well as for off-line analysis of stored images. It provides a quantitative framework based on fourier transform feedback for monitoring SEM resolution, astigmatism and image quality over time and as compared to other instruments. Information from the software analysis can be used to adjust a SEM for optimum performance.

SEM Monitor calculates sharpness, eccentricity, eccentricity orientation, and kurtosis. It presents results for real-time or archived images numerically, graphically and stores the results in database. It produces SEM Focus and Astigmatism Measurements. The SEM Monte Carlo Model automatically finds the best fit of measured and modeled line scans depending on the beam parameters of the SEM and electron detection. Using this capability, an extensive modeled library of production samples can be created. SEM Monitor can also measure linewidths and apparent beam width (ABW) using various algorithms.

The SEM Monitor Software implemented by Spectel is based on techniques developed by respected industry technologists, Michael Postek and Andras Vladar, for SEM performance analysis. Spectel has worked closely with the SEMATECH Scanning Electron Microscope User's Group in defining tool requirements and has collaborated with NIST and Hewlett Packard ULSI Laboratories in the product development.

The SEM Monitor software is available for operation in a Windows NT or Windows 95 environment.

Current Technical Papers

Use of Fast Fourier Transform Methods in Maintaining Stability of Production CD-SEMS
Benjamin D. Bunday, Conexant Systems, Inc., Newport Beach, CA
Mark Davidson, Spectel Company, Mountain view, CA 94043

SPIE Microlithography Conference, February, 2000.

Utilizing Fast Fourier Transform Methods embodied in SEM-Monitor, Conexant Systems controlled SEM beam tuning such that repeated measurements of 0.18 µm linewidths varied by only 2nm. Long-term precision-to-tolerance (P/T) of 2-3nm was achieved through monitoring CD-SEM beam quality with the SEM Monitor’s sharpness and eccentricity calculations.
ConexantSEMMonitorPaper.pdf

Improving Stigmation Control of the CD- SEM
B.Choo, S.Punjabi, B.Singh, M.Tempelton Submicron Development Center, AMD, Sunnyvale, CA
Mark Davidson, Spectel Research, Mountain View, CA

SPIE Microlithography 2000

The sharpness and eccentricity data provided by SEM Monitor provides an objective standard for adjusting SEM stigmation resulting in more consistent SEM measurements. Risk of erroneous measurements is reduced using SPC charts for SEM sharpness and eccentricity values.
AMDSEMMonitorPaper.pdf

For detailed information on SEM Monitor, download semmoninfo.exe which is a self extracting zip file. Technical references: Postek, M.T. and Vladar, A.E. 1996a. SEM sharpness evaluation. Proceedings MSA 1996 (Bailey, Corbett, Dimlich, Michael and Zaluzek, eds) 142-143;
Postek, M.T. and Vladar, A.E. 1996b. SEM sharpness evaluation.