Spatial-phase-locked electron-beam lithography: Initial test results

Abstract

Earlier spatial-phase-locked e-beam lithography (SPLEBL) was proposed as a means of eliminating the well-known problem of feature placement precision in scanning electron-beam lithography. In SPLEBL, a grid with long-range spatial-phase coherence is created on a substrate (or on top of its resist coating) and this grid is used to feedback information on beam location to the control system. In initial tests a standard deviation (σ) of 0.3 nm for phase-locking precision in one dimension was demonstrated, which represents the finest field stitching ever obtained with any lithographic method. In two dimensions (2D), σx, σy=0.6, 0.4 nm was obtained. Moiré spatial-phase locking was also demonstrated in 2D. Two strategies for the global-fiducial grid appear feasible: plating base modulation and a thin film of holographically exposed photoresist on thin-film Al above the e-beam resist. Either would permit spatial-phase locking without exposure of resist.