Laboratory-Based Three-Dimensional Imaging of Semiconductor Materials with 80 nm Resolution Using Transmission X-ray Microscopy
F. Duewer, M. Feser, S. Kamath, C. Kelly, A. Lyons, S. Neogi, P. Pombo, D. Scott, D. Trapp, S. Wang and W. Yun
Keywords: x-ray, microscopy, semiconductor, characterization, tomography
Xradia has developed a commercially available tomographic transmission x-ray microscope operating at 5.4 keV using a laboratory source. It is capable of imaging buried copper features with resolution better than 80 nm through more than 20 um of silicon. The ability to nondestructively image buried conducting and insulating features with better than 80 nm resolution is a powerful feature of this laboratory-based system. At 5.4 keV, 100 nm copper layers can be resolved and the transmission of silicon is sufficient to allow imaging. While similar capabilities have been demonstrated using synchrotron-based radiation sources, Xradia is the first to develop this capability in a laboratory-based instrument. The microscope is a zone-plate based transmission x-ray microscope, consisting of a x-ray source, condenser assembly, zone plate, and scintillating detector. It offers high spatial resolution and high throughput. For two dimensions, better than 80 nm spatial resolution has been demonstrated. A single two dimensional image requires 15 minutes for 1% contrast. Three dimensional tomographic reconstructions have been obtained. In three dimensions, similar x-y resolution has been obtained, though the z resolution is limited to 200 nm. Images of sub-80 nm voids in electromigration samples have been obtained.
Nanotech 2004 Conference Technical Program Abstract