Improving SEM Image Quality Using Pixel-Super Resolution Technique

摘要

The most decent scanning electron microscopy (SEM) can provide image magnification up to 500kX which seems to be suitable to image semiconductor devices for the advanced technology nodes. However, SEM images at such a high magnification often suffer from the drift and space related displacement errors, potentially causing image blur and distortion. To circumvent this, we apply the super-resolution (SR) technique to enhance the resolution of the CD-SEM metrology by using the advanced signal processing algorithms. The resolution enhancement can be realized by exploiting the multiple low resolution (LR) images that include unique information of an imaging target by looking at a slightly different position. We experimentally demonstrate image quality improvement gained by the SR technique after correcting the time-dependent drift/displacement and mapping estimated information onto the high resolution (HR) pixel grid with the non-linear pixel interpolation scheme. In addition, estimating the time-dependent drifts of the wafer position could be useful to investigate the drift properties of the CD-SEM tool.