NEXT>There are three big differences between a SEM and a big beam writer: speed, accuracy, and automation. The low bandwidth of SEM deflectors allows the instrument to write fine lines, but the catch is that those lines may not land where you want them. It’s like an uncertainty principle: low noise and low bandwidth lead to a larger uncertainty in placement, since the beam takes longer to settle after deflection. The SEM also has problems building large patterns out of small writing fields. If a pattern is built up from multiple exposure fields then the SEM will stitch those fields together poorly, compared to the dedicated system. Ease of use is a more subjective matter, but most people agree that the big systems are easier to use. They are certainly a lot faster, especially since they include automated calibration routines.