We have developed a method of cross-sectioning silicon wafers with high placement precision. It is implemented by using optical lithography and deep plasma high aspect ratio etching of a thin line, which is used as the breaking axis. This technique is then applied to cross-sectional scanning electron microscopy (SEM) studies of sub-50 nm electron beam lithography in (poly)methylmethacrylate resist. We also report the development of a process for protecting the resist during SEM examination.