Direct observation of 3D nitrogen distribution in silicon-based dielectrics using atom probe tomography

Area of Science:

• Materials Science
• Semiconductor Physics
• Analytical Chemistry

Background:

• Nitrogen distribution is key to semiconductor properties but challenging to analyze at interfaces.
• Existing methods struggle to distinguish nitrogen from silicon in atom probe tomography without isotope doping.

Purpose of the Study:

• To precisely characterize the 3D nitrogen distribution in semiconductor device structures.
• To understand the impact of nitrogen distribution on device performance and reliability.

Main Methods:

• Utilized advanced atom probe tomography with an extended flight path and optimized conditions.
• Analyzed nitrogen distribution in silicon dioxide/silicon oxynitride gate dielectrics (2- and 5-nm thick) and fin-structured devices.

Main Results:

• Successfully mapped the 3D nitrogen distribution at atomic scales.
• Demonstrated that nitrogen distribution dictates the nitrogen profile in gate dielectrics.
• Showed that nitrogen profiles influence impurity diffusion and ultimately device electrical properties and reliability.

Conclusions:

• Advanced atom probe tomography enables precise nitrogen quantification in complex semiconductor structures.
• Atomic-scale nitrogen behavior is critical for optimizing semiconductor device performance and reliability.
• Insights gained pave the way for developing advanced next-generation semiconductor devices.