The influence of different SEM parameters on CD measurement results

The increasing complexity and the resulting reduction in feature dimensions mean that the already wide field of application of a Scanning Electron Microscope (SEM) is extended to that of metrology. In many cases, due to its higher lateral resolution and the increased depth of focus, Critical Dimension (CD) data can only be acquired using a SEM instead of optical systems. The correct evaluation of the obtained results requires a detailed knowledge about the influence of different SEM parameters, such as primary electron (PE) energy, beam diameter, focus etc., on the video profiles. Up to now, the complexity of the profile variations due to a change in SEM parameters do not allow a fast and convenient compensation by the software. This makes it necessary to calibrate the system after a variation of SEM settings.