Spatial-phase locking with shaped-beam lithography

Spatial-phase-locked electron-beam lithography is a method of precisely locating pattern elements on a substrate by providing real-time feedback of the beam’s location by means of a fiducial grid located on the substrate surface. Previously, this technique has been demonstrated in Gaussian-beam systems, in one and two dimensions. In this note we propose a method of extending the spatial-phase-locking concept to a vector shaped-beam architecture. In the proposed method, an image of a screen grid is superimposed on the projected shape, and this grid image is dithered in X and Y to provide a periodic signal whose phase can be interpreted to determine the position of the projected shape relative to the fiducial grid.