Improved system availability and performance by optimized single servo calibration test

摘要

An electron microscope (EM) uses a beam of accelerated electrons to illuminate samples and produce images. As the wavelength of an electron beam is much shorter than that of a visible light source, an EM is able to provide a much higher resolving power than a conventional light microscope and can thus reveal sub-nanometre structures. Such an excellent resolution makes EMs a widely used inspection fool for many different industries such as semiconductor industry. For example, product wafers with nanometre (nm) scale defects are inspected after production by using scanning electron microscopes (SEMs), a type of EM, to ensure a satisfactory quality is achieved. In order to accurately inspect a semiconductor wafer, it is desirable to position the semiconductor wafer precisely and accurately.