Ultra-thin SiON and high-k HfO2 gate dielectric metrology using transmission electron microscopy

Ultra-thin nitrided SiO₂ (10 Å SiON) and high-k HfO₂ gate dielectric thin film metrology and chemical characteristics are studied using transmission electron microscopy (TEM). Different specimen preparation methods and TEM analytical techniques are compared to understand their impacts on the results. Ultra thin SiON thickness measured by using high resolution TEM (HRTEM), is different from results obtained by high resolution scanning TEM (HR-STEM) using high-angle annular dark field detector (HAADF) and also different from using electron energy loss spectrometry (EELS). A standard TEM metrology approach for ultra-thin gate dielectric needs to be established throughout the industry and best practices are suggested.