Study on optical reflection property from multilayer on Si substrate including nanoparticles in SiO 2 layer

Abstract

Metal nanoparticles are formed in a thin SiO 2 layer such as gate oxide layer on silicon substrate in application to silicon-based single electron devices. A nondestructive method is required for monitoring the nanoparticle state such as particle size and distribution depth. Here, optical reflection property from multiple layer structure on Si was studied by experiments and with theoretical analysis. We have proposed a calculation method of the reflectance from Ag implanted 50-nm-thick SiO 2 film on Si substrate with three-layers model of the top SiO 2, a composite layer with Ag nanoparticles, and bottom SiO 2 layer. The experimentally obtained reflectance spectra from samples at 30 keV–1 × 10 16 and 1 × 10 17 ions/cm 2 are well fitted by the proposed analysis as changing particle size and distribution depth based on the depth profiles of implanted atoms.