Abstract
Carrier mobility enhancement through local strain in silicon is a means of improving transistor performance. Among the scanning probe microscopy based techniques, tip-enhanced Raman spectroscopy (TERS) has shown some promising results in measuring strain. However, TERS is known to depend critically on the quality of the plasmonic tip, which is difficult to control. In this study, a test structure is used to demonstrate the capability of photo-induced force microscopy with infrared excitation (IR PiFM) in direct measurement of strain with approximately 10 nm spatial resolution. For SiGe pitch less than about 800 nm, the region between the SiGe lines should maintain residual strain. For a region with SiGe pitch of 1000 nm, it is verified that the strain between the SiGe lines is fully relaxed. PiFM promises to be a powerful tool for studying nanoscale strain in diverse material.
