Study on optical reflection property from multilayer on Si substrate including nanoparticles in SiO_2 layer

摘要

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 x 10~(16) and 1 x 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.