Amplitude and phase beam shaping for highest sensitivity in sidewall angle detection.

Area of Science:

• Semiconductor Manufacturing
• Optical Metrology
• Integrated Circuit Fabrication

Background:

• Lithography is crucial for integrated circuit (IC) manufacturing.
• Accurate measurement of structure sidewall angles is essential for process quality control.
• Current methods face limitations in detecting subtle sidewall angle variations.

Purpose of the Study:

• To investigate the potential of a shaped cylindrically focused probing beam.
• To enhance the detection sensitivity of sidewall angle changes.
• To improve the accuracy of lithographic process evaluation.

Main Methods:

• Utilizing scalar diffraction theory for analysis.
• Modeling cliff-like structures as phase objects.
• Developing a theoretical formulation for an optimized probing beam.
• Comparing the optimized beam's performance against a focused plane wave.

Main Results:

• The cylindrically focused probing beam demonstrates increased sensitivity to minute changes in sidewall angle.
• The proposed beam offers a significant improvement over traditional focused plane waves for this specific measurement.
• Theoretical calculations provide a framework for optimizing beam design.

Conclusions:

• A properly shaped cylindrically focused probing beam can significantly improve the detection of sidewall angle inaccuracies.
• This optical metrology approach offers a promising advancement for integrated circuit manufacturing quality control.
• Further research can explore experimental validation and broader applications.