Development of a wafer warpage measurement technique using Moiré-based method

Area of Science:

• Semiconductor manufacturing
• Metrology
• Optical engineering

Background:

• Wafer warpage is a critical parameter in semiconductor manufacturing, affecting device performance and yield.
• Existing measurement techniques for wafer warpage often lack sufficient resolution, stability, or flexibility.
• Accurate and precise measurement of wafer warpage is essential for quality control and process optimization.

Purpose of the Study:

• To introduce a novel, high-resolution technique for measuring wafer warpage.
• To enhance the accuracy, stability, and flexibility of wafer warpage measurements.
• To demonstrate the effectiveness of the proposed method through experimental validation.

Main Methods:

• The technique combines moiré shift, digital moiré, autocollimator, and scanning profiling.
• An optical moiré system projects a grating onto the wafer, captured by a CCD camera.
• A phase analysis system detects phase shifts in moiré fringes, correlating them to warpage.

Main Results:

• The proposed method achieves an angular resolution of 0.2 μrad.
• Experimental results confirm high measurement resolution, stability, and flexibility.
• The system effectively measures wafer warpage across the entire surface.

Conclusions:

• The novel technique provides a significant advancement in wafer warpage metrology.
• The method's high resolution and flexibility make it suitable for advanced semiconductor fabrication.
• This approach offers a robust solution for quality assurance in wafer manufacturing.