Reducing focused ion beam charging effects on insulators by heating: A practical method for TEM specimen preparation of nonconductors

• Published in: Ultramicroscopy 1988, Vol.24 (1), p.27-36
• Main Authors: Lundquist, T.R., Alani, R., Swann, P.R.
• Format: Article
• Language: English
• Subjects: Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Other methods of structure determination; Physics; Structure of solids and liquids; crystallography
• ISSN: 0304-3991; 1879-2723
• DOI: 10.1016/0304-3991(88)90324-5

Heating has been investigated as a method to reduce charging effects on nonconductors so that they can be imaged via a focused ion beam and, thereby, precision-ion-milled to obtain localized, electron transparent areas. Discharge mechanisms have been examined by measuring secondary yields as a function of temperature to gain understanding as to how heating improves imaging. Imaging via secondary ions generally required temperatures above 200°C and imaging via secondary electrons required temperatures above 300°C. Different materials require different discharge mechanisms to negate charging and, therefore, must be examined individually to determine their suitability for imaging at elevated temperatures as some materials are modified, if not destroyed, at high temperatures. The discharge mechanisms we identified include mobile ion migration, thermal ion emission from the specimen and thermal electron emission from the specimen holder. Finally the usefulness of heating is demonstrated by thinning a small area of a TEM alumina ceramic specimen to electron transparency. Electron and ion beam technologies can benefit from this finding.