Nanoscale strain characterization in microelectronic materials using X-ray diffraction

Abstract

The engineering of strained semiconductor materials represents an important aspect of the enhancement in CMOS device performance required for current and future generations of microelectronic technology. An understanding of the mechanical response of the Si channel regions and their environment is key to the prediction and design of device operation. Because of the complexity of the composite geometries associated with microelectronic circuitry, in situ characterization at a submicron resolution is necessary to verify the predicted strain distributions. Of the measurement techniques commonly used for strain characterization, synchrotron-based X-ray microbeam diffraction represents the best nondestructive method to provide spatially resolved information. The mapping of strain distributions in silicon-on-insulator (SOI) features induced by overlying silicon nitride structures and embedded heteroepitaxial features adjacent to SOI device channels are presented. The interaction regions of the SOI strain were observed to extend large distances from the SOI/stressor interfaces leading to significant overlap in the strain distributions at technically relevant dimensions. Experimental data were also compared to several mechanical models to assess their validity in predicting these strain distributions.