Method of producing an un-distorted dark field strain map at high spatial resolution through dark field electron holography

摘要

An inline dark field holographic method for measuring strain in a semiconductor or other crystalline material using a transmission electron microscope having an electron gun for passing an electron beam through strained and unstrained specimens. A condenser mini-lens between the magnetic tilting coil and the specimens increases defection of the beam at an angle with prior to passing through the pair of specimens. The first objective lens forms a virtual image of each of the specimens and the second objective lens focuses the virtual images of each of the specimens at an intermediate image plane to form intermediate images of each of the specimens. The biprism creates the interference pattern between the specimens is formed at the image plane, which may then be viewed to determine the degree of strain of the strained specimen and provides a coma-free strain map with minimal optical distortion.

主权项

1. An inline dark field holographic method for measuring strain in a semiconductor material or other crystalline materials comprising:
providing a transmission electron microscope having an electron gun for passing an electron beam along an axis through at least one specimen, a magnetic tilting coil for deflecting the beam at an angle with respect to the axis, first and second spaced objective lenses along the beam axis, and a biprism for combining a portion of the electron beam transmitted through the specimen with a portion bypassing the specimen; providing a condenser mini-lens between the magnetic tilting coil and the specimen for increasing defection of the beam at an angle with respect to the axis; providing a pair of specimens of the semiconductor material, one specimen having a strained crystal structure to be measured and the other specimen having an unstrained crystal structure; with the magnetic tilting coil, deflecting the electron beam at an angle with respect to the axis; with the condenser mini-lens, deflecting the electron beam from the magnetic tilting coil at an additional, higher angle with respect to the axis prior to passing through the pair of specimens; with the first objective lens forming a virtual image of each of the specimens; with the second objective lens focusing the virtual images of each of the specimens at an intermediate image plane to form intermediate images of each of the specimens; with the biprism, causing the intermediate images of each of the specimens to overlap such that an interference pattern between the specimens is formed at the image plane; and viewing the interference pattern and determining the degree of strain of the strained specimen.