Electron diffraction with ten nanometer beam size for strain analysis of nanodevices

A method to perform nanobeam diffraction (NBD) in a transmission electron microscope with high spatial resolution and low convergence angle is proposed. It is based on the use of a properly fabricated condenser aperture of $1μm$ in diameter, which allows an electron beam about $10nm$ in size to be focused on the sample, with a convergence angle in the $0.1mrad$ range. Examples of NBD patterns taken in an untilted ⟨110⟩ cross section of a silicon device are shown. Their quality is adequate for spot position determination and hence to obtain, in principle, quantitative strain information.