On the preparation of cross-sectional TEM samples using lithographic processing and reactive ion-etching

Abstract

Preparation of cross-sectional TEM samples has been completed without use of the normal means of mechanical polishing and ion-milling. Instead, lithographic processing and reactive ion-etching (RIE) were used to define thin walls ranging from 100 to 1000 nm in width which protruded 1 μm from the substrate surface. The substrate was cut into pieces suitable for securing them into a standard double-tilt holder so that the etched walls were exposed to the electron beam and images could be formed. Samples have been made using both electron beam and optical lithography with different dry etching processes to define thin walls of composite layers of Si, Si 3N 4 and SiO 2 and also a thin film of Al-Cu(2 wt%). The results present a promising new method for preparation of cross-sectional TEM samples that is less labor-intensive and more productive than mechanical polishing and ion-milling.