True Large-Area SEM with various detectors
The Laser Interferometer Stage is an undeniably important ingredient of any professional nanolithography system. When reversing the functionality of an EBL tool from writing to imaging, it is also a critical component for accurately stitching SEM images over large areas because it allows the sample to be accurately positioned under the field of view (FOV). Moreover, it is used to map out errors in the FOV to a measurement accuracy of 1 nm.
Various detectors – whether secondary or backscattered detectors – help to achieve the best image contrast or to extract the optimum analytical information. Laser height measurement and corresponding automatic sample height adjustment to an accuracy of better than 1 μm ensures focus stability over an entire sample such as a large wafer, even if the sample is inclined or exhibits a strong curvature such as a wafer bow.