Motion-free all optical inspection system for nanoscale topology control

Area of Science:

• Optics and Photonics
• Nanotechnology
• Metrology

Background:

• Accurate nanoscale pattern inspection is crucial for semiconductor manufacturing and materials science.
• Existing methods often rely on mechanical scanning, which can introduce errors and limit throughput.
• Developing non-contact, high-precision inspection techniques is an ongoing challenge.

Purpose of the Study:

• To present a novel, all-optical method for nanoscale pattern inspection.
• To demonstrate the use of chromatic aberration and a tunable light source for precise measurements.
• To evaluate the performance and accuracy of this new optical inspection technique.

Main Methods:

• Utilizing chromatic aberration in an imaging optical system.
• Employing a low-cost, tunable light source (LED bandwidth ~30 nm FWHM) for controlled defocusing.
• Analyzing defocused diffraction patterns of nanoscale objects.

Main Results:

• Achieved stable and precise inspection of nanoscale objects without mechanical influence.
• Demonstrated measurement accuracy better than 10 nm for calibrated lines (40-150 nm critical dimension).
• Validated the method using calibrated lines on a monocrystalline silicon substrate.

Conclusions:

• The proposed all-optical method offers a viable alternative to mechanical scanning for nanoscale inspection.
• This technique enables high-accuracy, non-contact metrology for critical dimension measurements.
• The use of readily available components like tunable LEDs makes the method cost-effective.