LAUSR

Technology advances in the semiconductor industry are motivated by minimization of feature size and optimization of process time. This is well captured in the recent literature by the statement that expectations for metrology data are “as precise as possible” and “as fast as possible” [1]. Ideally, this applies to all measurements ranging from statistical process control (SPC) methods to more esoteric methods used for failure analysis or development feedback. This is not feasible, of course, and we settle for using fast, non-invasive methods for SPC and revert to slower, often destructive, but also often more informative, methods in situations where high spatial resolution information is required. It is highly desirable to have an understanding of the level of correlation across such measurements. In this work we explore indium concentration (or dose) correlation for InGaAs finFET type test structures (Fig. 1) using low energy electron probe microanalysis (LEXES) [2], scanning transmission electron microscopy (STEM), secondary ion mass spectrometry (SIMS) [3,4], and atom probe tomography (APT) [5]. Fig. 2 shows example high angle annular dark field STEM images for InGaAs fin widths of 20 nm (a) and 100 nm (b). Nominal In-layer concentrations (Fig. 3) are x=15 at.% and y=25 at.% (y varies with fin width).