Stress Distribution Profile Imaging With Spectral Fabry-Perot Interferometry in Thin Layer Substrates for Surface...

Area of Science:

• Materials Science
• Optical Metrology
• Semiconductor Physics

Background:

• Thin film stress significantly impacts device performance and reliability in silicon wafers.
• Accurate characterization of stress distribution profiles (SDPs) is crucial for fabricating high-quality semiconductor devices.
• Existing methods for stress evaluation can be time-consuming or destructive.

Purpose of the Study:

• To introduce and validate spectral two-layer interferometry (STLI) as a fast, all-optical method for SDP estimation.
• To demonstrate the capability of STLI for nondestructive evaluation of pre-stress topography in silicon wafers.
• To systematically assess the consistency and robustness of STLI for polycrystalline silicon (PS) and silicon nitride (SN) thin films.

Main Methods:

• Utilizing spectral two-layer interferometry (STLI) imaging for optical measurement of stress.
• Applying STLI to silicon wafers deposited with thin films, specifically polycrystalline silicon (PS) and silicon nitride (SN).
• Comparing STLI-derived SDP estimations with complementary characterization techniques for validation.

Main Results:

• STLI provides a fast and reliable all-optical methodology for SDP estimation in thin film substrates.
• The technique demonstrates a nondestructive, systematic, and robust capability for consistent SDP evaluation in PS and SN films.
• SDP estimations using STLI are consistent and validated through complementary characterization of the films.

Conclusions:

• Spectral two-layer interferometry (STLI) is a highly effective, non-destructive technique for evaluating stress distribution profiles in thin films.
• This all-optical method offers significant advantages in speed and reliability for semiconductor wafer characterization.
• STLI provides a robust platform for consistent stress analysis in critical thin film materials like PS and SN.