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

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. Moire 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.