Large-field and high-resolution low-voltage scanning electron microscopy with correction of beam-image-shift-induced chromatic deflection aberration

Abstract

We present a chromatic deflection aberration-free beam-image-shifting technique for low-voltage scanning electron microscopy. The technique utilizes a Wien filter to correct the chromatic deflection aberration induced by the beam-image shift. Experimental results demonstrated that this method significantly improves spatial resolution across a large field of view (FOV) of 28 × 28 μm2, covered by the beam-image shift. By correcting the chromatic deflection aberration, the degradation rate of the spatial resolution at the corner of the FOV relative to its center reduced from a maximum of 16% to 8%. The developed Wien filter responded 60% faster than the beam-image shift, eliminating the need for additional settling time for correction. Furthermore, we applied the presented technique to semiconductor pattern measurement and showed significant potential to improve the critical dimension uniformity in the FOV covered by the beam-image shift. We believe that the proposed method provides a practical and cost-effective amelioration as a beam-image-shifting technique.