High-resolution, electron-microscopic methods (Figure 1) are employed wherever optical investigation methods no longer suffice in structural investigations and where suitable specimen preparation is possible. Due to their extremely high resolution, it is even possible to detect the distances between individual atoms. Transmission electron microscopes (TEM) achieve resolutions down to 0.1 nm, scanning electron microscopes (SEM) achieve resolutions up to a range of 1 nm, and are thus considerably better than optical methods. Confocal light microscopy generally achieves between 200 to 300 nm, optical super resolution with commercial systems achieves down to 20 nm.
Typical applications for electron microscopy are widespread today, extending well beyond research applications into industrial applications such as surface and structure inspection in semiconductor technology and materials research as well as the field of life sciences. In combination with an ion beam, even three-dimensional investigations are possible, whereby the ion beam removes individual layers of the specimen. In the case of minute structures on semiconductors, this allows determining layer thicknesses by counting the number of superimposed atom layers. In the field of life sciences the smallest cell structures are made visible. The specimens can, among other methods, be prepared with special freezing processes.
Stable Positioning and High Repeatability
And the various applications all have one thing in common: increasingly automated inspection processes require flexible and reliable drive solutions which must operate under conditions of vacuum and ideally be lubrication-free and non-magnetic. In the case of TEM, the specimen needs to be kept as stable as possible. Manipulation of specimens in the nanometer range is obligatory, after all, the viewing field is only 150 nm.