Modeling and simulation of infrared reflectance spectra of deep trench structures of DRAM

This paper proposes a nondestructive technique for measuring deep trench structures of DRAM using infrared reflectance spectrometry. By processing layered-film optical model equivalents of various trench array structures with effective medium theory, the reflectance spectra of optical models are accurately simulated with Fresnel–s reflection equations, and the relationships between modeled spectra and trench geometric parameters are analyzed. It is fully expected that this technique will be simple to implement and will provide a useful practical tool for the in-line measurement and process control on product wafers.