Large Area Plan-View Transmission Electron Microscopy Sample Preparation for Direct-Bonded Interfaces

Abstract

A focused ion beam (FIB) sample preparation technique is developed to produce large areas of electron transparent material for plan-view transmission electron microscopy measurements from direct-bonded interfaces without thinning the bonded wafers. A FIB cut allows plan-view sample creation from the bonded interface region, and therefore rapid characterization of the defect density as a function of bonding conditions, substrate miscut, or pre-bonding surface treatments. Uniform electron transparent plan-view areas are extracted from the interface region to facilitate observation of the interface reconfiguration. To demonstrate the technique, the electrically active interfaces of a series of bonded III-V structures is studied as a function of substrate miscut as well as in-plane misorientation. Distinct differences in the interface reconstruction are observed and the interface reconstruction produces screw and edge dislocation networks at the III-V interfaces. The degree of twist and tilt is confirmed with both cross section electron microscopy measurements as well as in-plane x-ray diffraction measurements.