There has been much recent work in developing advanced optical metrology applications that use imaging optics for optical critical dimension (OCD) measurements, defect detection, and for potential use with in-die metrology applications. We have previously reported quantitative measurements for sub-50 nm CD dense arrays which scatter only the 0th-order specular diffraction component using angle-resolved scatterfield microscopy. Through angle-resolved and focus-resolved imaging, we now access the three-dimensional scattered fields from OCD targets that contain multiple Fourier frequencies. Experimental sensitivity to nanometer scale linewidth changes is presented, supported by simulation studies. A new, more advanced approach to tool normalization is coupled with rigorous electromagnetic simulations and library based regression fitting that potentially enables OCD measurements with sub-nanometer uncertainties for targets that scatter multiple Fourier frequencies.
Proceedings Title: Instrumentation, Metrology, and Standards for Nanomanufacturing IV, Proceedings of SPIE Volume: 7767
Conference Dates: August 12-17, 2012
Conference Location: San Diego, CA
Conference Title: SPIE Optics & Photonics 2012
Pub Type: Conferences
optical metrology, electromagnetic simulation, frequency domain tool normalization, multiple frequency scattering, evaluate sensitivities and uncertainties, phase sensitive measurements