Improved Optical Model for SiO₂/Si Ultra-Thin Film Thickness Determination by Spectroscopic Ellipsometry

Abstract:

Different optical models were adopted to fit theoretical simulation curves of a SiO₂ ultra-thin film with a density of 2.2 g/cm³ and a thickness of 6nm grown on Si wafer. The results indicate that thickness obtained from fitting decrease linearly with increase of film density. An improved optical model (density of thin film of 2.4g/cm³, roughness of surface of 0.4nm, roughness of surface of 0.3nm) was obtained according to the above analysis and the GIXRR results of our previous work. The improved model could give more accurate thickness value of ultrathin film with thickness less than 10nm. It was employed in the thickness fitting for thermal oxidized SiO₂/Si thin film with nominal thicknesses of 2, 4, 6, 8 and 10nm. The results were 2.61, 4.07, 6.02, 7.41 and 9.43nm, decreased by 13.8%10.3%8.1%7.3% and 6.6%, respectively, compared with the results calculated from the traditional model.

• Periodical: Advanced Materials Research (Volumes 915-916)
• Pages: 803-807
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.915-916.803
• Online since: April 2014
• Authors: Jiang Wei Fan*, Qin Lei Sun, Mei Quan Liu
• Keywords: Multilayer Model, SiO₂/Si Ultra Thin Film, Spectroscopic Ellipsometry, Thickness

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