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 crucial in semiconductor manufacturing.
• The SiO2/Si interface is fundamental to microelectronic device performance.
• Quantifying interface roughness impacts device reliability and electrical properties.

Purpose of the Study:

• To develop and validate a model for determining SiO2/Si interface roughness.
• To quantitatively measure the root-mean-square (rms) roughness of the front surface and the oxide-substrate interface.
• To assess the agreement between calculated and experimental diffuse reflectance spectra.

Main Methods:

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

Main Results:

• Quantitative interface roughness values were obtained from diffuse reflectance spectra.
• Excellent agreement was achieved between calculated and experimental spectra.
• Determined an rms roughness of 9.0 nm for the front surface and 2.2 nm for the SiO2/Si interface.

Conclusions:

• The developed optical model provides an effective method for quantifying SiO2/Si interface roughness.
• The technique is suitable for characterizing low-pressure, low-temperature Chemical Vapor Deposition (CVD) SiO2 films.
• Accurate interface roughness measurements are vital for optimizing semiconductor fabrication processes.