Determination of the SiO(2)/Si interface roughness by diffuse reflectance measurements

Area of Science:

• Materials Science
• Optics
• Surface Science

Background:

• Accurate characterization of interfaces is critical in semiconductor fabrication.
• The SiO(2)/Si interface is fundamental to microelectronic devices.
• Quantifying interface roughness impacts device performance and reliability.

Purpose of the Study:

• To develop and validate a model for determining SiO(2)/Si interface roughness.
• To extract quantitative roughness parameters from diffuse reflectance spectra.
• To assess the applicability of Fresnel formalism and scalar scattering theory for interface analysis.

Main Methods:

• Utilized a model based on Fresnel formalism and scalar scattering theory.
• Calculated diffuse reflectance as a function of optical constants, oxide thickness, and interface roughness.
• Employed roughness values as adjustable parameters to fit experimental diffuse reflectance spectra.

Main Results:

• Developed formulas relating diffuse reflectance to interface properties.
• Obtained quantitative interface roughness values for an SiO(2)/Si double layer.
• Achieved excellent agreement between calculated and experimental spectra for a specific CVD film.

Conclusions:

• The model successfully quantifies interface roughness.
• Determined an rms roughness of 9.0 nm at the front surface and 2.2 nm at the SiO(2)/Si interface.
• The approach is effective for characterizing thin dielectric films on silicon substrates.