An experimental automatic registration system is discussed that is capable of precisely overlaying two or more levels of a microcircuit pattern written by an electron-beam lithographic machine. Because positional information of the registration marks arrives at the detector in the form of random discrete quanta, it is subject to the statistical fluctuations inherent in all such systems. Achievement of a signal-to-noise ratio adequate for precise registrations with inherently noisy backscattered electrons and without overexposure of the resist layers covering the registration mark is accomplished using digital signal enhancement techniques. Manual and computer methods have been developed to correct field size, shift, rotation, and orthogonality. Correlation between manual and automatic registrations and the pattern are excellent because the same basic deflection and electronics systems are used for all three modes of operation. The necessary software to control the registration subsystems and to perform registration computations and edge detection have also been developed. Registration overlays have been made automatically with absolute errors on the order to 100 ppm. For a 2-mm chip, this is a level-to-level error of about ±0.1 μm. Several samples of typical complex microcircuit patterns registered with this experimental automatic system are shown.