Precise Linewidth Measurement Using a Scanning Electron Probe

Fumio MIZUNO  Satoru YAMADA  Akihiro MIURA  Kenji TAKAMOTO  Tadashi OHTAKA  

IEICE TRANSACTIONS on Electronics   Vol.E76-C   No.4   pp.600-606
Publication Date: 1993/04/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Sub-Half Micron Si Device and Process Technologies)
Category: Process Technology
LSI,  metrology system,  scanning electron probe,  measurement accuracy,  reproducibility,  linearity,  repeatability,  

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Practical linewidth measurement accuracy better than 0.02 µm 3 sigma that meets the production requirement for devices with sub-half micron features, was achieved in a field emission scanning electron-beam metrology system (Hitachi S-7000). In order to establish high accuracy linewidth measurement, it was found in the study that reduction of electron-beam diameter and precise control of operating conditions are significantly effective. For the purpose of reducing electron-beam diameter, a novel electron optical system was adopted to minimize the chromatic aberration which defines electron-beam profile. As a result the electron beam diameter was reduced from 20 nm to 16 nm. In order to reduce measurement uncertainties associated with actual operating conditions, a field emission electron gun geometry and an objective lens current monitor were investigated. Then the measurement uncertainties due to operating conditions was reduced from 0.016 µm to 0.004 µm.