Microsphere-assisted, nanospot, non-destructive metrology for semiconductor devices

Area of Science:

• Semiconductor metrology
• Optical physics
• Nanotechnology

Background:

• Semiconductor industry trends towards smaller structures and 3D integration.
• Optical metrology, including spectroscopic ellipsometry (SE), is crucial for 3D structure measurements.
• Existing SE techniques require smaller spot sizes to measure in-cell critical dimension (CD) variations in dynamic random-access memory (DRAM).

Purpose of the Study:

• To develop an ultra-small spot spectral metrology system for advanced semiconductor devices.
• To overcome the limitations of current SE spot size for in-cell CD variation monitoring.
• To enable precise metrology for next-generation memory and logic devices.

Main Methods:

• Utilized a microsphere-assisted super-resolution effect for spectral metrology.
• Achieved an extremely small spot diameter of approximately 210 nm.
• Developed a geometric model to optimize imaging quality by calculating magnification and depth of focus.

Main Results:

• Demonstrated an ultra-small spot spectral metrology system with a ~210 nm spot diameter.
• Maintained a high signal-to-noise ratio with the reduced spot size.
• Verified the system's effectiveness through simulations and experiments on various samples.

Conclusions:

• The microsphere-assisted spectral metrology technique offers a solution for monitoring in-cell CD variations.
• This ultra-small spot metrology capability is vital for advanced logic and memory devices.
• The developed geometric model aids in optimizing the metrology system for superior imaging quality.