Nanoscale stress field evaluation with shallow trench isolation structure assessed by cathodoluminescence spectroscopy, Raman spectroscopy, and finite element method analyses

Stress engineering related to the LSI process is required. With shallow trench isolation (STI) structures, a high stress field causes a variation in electrical characteristics. Although stress fields in a Si substrate can be detected by Raman spectroscopy, no effective technique has been reported for the measurement of nanoscale stress fields in a dielectric material used for STI filling. Recently, we have reported that "cathodoluminescence (CL) spectroscopy" enables us to detect nanometer-scale stress fields in LSI structures. In this study, we performed the first estimation of the stress fields with a STI structure by CL and Raman spectroscopy, as well as finite element method (FEM) calculation. We were able to repeatedly acquire clear stress distributions by CL and Raman spectroscopy. Moreover, CL, Raman, and FEM results showed excellent agreement with one another, revealing that a large variation in stresses along the AA/STI boundary was induced by the intrinsic tensile stress of the SiO2 film.