Transmission electron microscopy (TEM) is an important technique for studies of extended defects and other microstructural features in semiconductor materials. An efficient, plan-view thinning technique is always desirable for these TEM studies. The problems associated with wet chemical thinning of silicon are often surface residues, pitting and rapid breakthrough. A controlled method for obtaining thin, plan-view TEM silicon samples by chemical thinning was developed and the method is described in this paper. Results indicate that the method minimizes the above cited problems and has several other advantages over previously reported thinning methods.