Characterization of charging-induced pattern positioning errors in advanced mask making

Abstract

Charging-induced pattern positioning errors (CIPPEs) from a 50-kV variable-shape e-beam writer on an opaque-MoSi-over-glass mask has been carefully characterized by directly measuring the pattern shifts using a high-accuracy mask registration tool. In addition, the reported behaviors associated with the CIPPEs, exponentially decaying in space and sign flipping with increasing pattern density (PD), another seldom-mentioned error component, behaving like a constant offset in space and becoming stronger with increasing PD, is found. The authors repeat the experiment with a charge dissipation layer coated atop the resist to experimentally explore the origins of these two phenomena and find that the exponential components, removable by the charge dissipating layer (CDL), result from the well-known resist charging effect but the constant offset, remain existing with the CDL, does not. From the result of Monte Carlo simulations, the constant component is speculated to result from blank charging. This finding can give important insights into the model-based charging effect correction as well as the effectiveness of the CDL.