只有焦平面始终精确保持不变,自动聚焦系统才能以需要的复现性测出结构的实际宽度。此外,跟手动调焦相反,它能大大缩短测量所化的时间,因为自动调焦系统能找到预定的焦平面位置。采用自动调焦系统除了纯技术需要之外,还考虑到经济因素。一个操作人员每天要对掩模和晶片进行几百次检验或测量,上述装置可以提高它的工作效率,将省下的时间用于更紧张的检验或测量。 Only the focal plane remains exactly the same at all times, and the autofocus system can measure the actual width of the structure with the required reproducibility. In addition, as opposed to manual focusing, it greatly reduces the time taken for measurement because the autofocus system can find the pre-defined focal plane position. In addition to purely technical needs, auto-focus systems also take into account economic factors. An operator examines or measures masks and wafers hundreds of times a day, and the devices increase their productivity and save time spent on tighter tests or measurements.