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.