A modified back-etch method for preparation of plan-view high-resolution transmission electron microscopy samples

A modified back-etch method is described that has been successfully used to prepare samples of thin films and nanoparticles on Si wafer substrates for examination by high-resolution transmission electron microscopy ( HRTEM). This process includes ultrasonic cutting, abrasive pre-thinning and a two-stage etching procedure. Unlike previous reports of back-etching methods, tetramethyl ammonium hydroxide, which has a very high-etching selectivity of Si to SiO2, is used for the final etching to allow removal of the Si without degradation of the SiO2 membrane. An innovative wrapping method is also described. This novel approach reduces the preparation time for HRTEM samples to < 1 h per sample for groups of 10 or more samples. As an example, the preparation of FePt nanoparticle samples for HRTEM imaging is described.