Strain mapping in MOSFETs by transmission electron microscopy

In this paper, we present two methods to map strain in MOSFETs at the nanometer scale. Aberration corrected high resolution transmission electron microscopy (HRTEM) coupled with Geometric Phase Analysis (GPA) provides sufficient signal/noise to measure the displacement fields accurately. Finite Element Method simulations confirm our measurements. The field of view is however limited to an area of 200 nm times 200 nm. To overcome this, we have developed a new technique called dark-field holography based on off-axis electron holography and dark-field imaging. This new technique provides us a better strain resolution than HRTEM (reaching 0.05%), a spatial resolution of 4 nm and a field of view of 1 mum.