Precision 3D surface measurement of step-structures using mode-locked femtosecond pulses

Young-Jin Kim, Minah Choi, Keunwoo Lee, Heesuk Jang, Jiyong Park, Seung-Woo Kim, Ailing Tian, Anand Asundi, Weiguo Liu, Chunmin Zhang
2015 The International Conference on Photonics and Optical Engineering (icPOE 2014)  
Fast, precise 3-D measurement of step-structures fabricated on microelectronic products is essential for quality assurance of semiconductor, flat panel display and photovoltaic products. Optical interferometers have long been used, but not that wide-spread for step-structures due to their phase ambiguity or low spatial coherence. Femtosecond pulse lasers can provide novel possibilities to optical profilometry both in the time and the frequency domain. In the time domain, stepsurfaces can be
more » ... ured over wide area by exploiting low temporal but high spatial coherence of femtosecond pulses; in the frequency domain, multi-wavelength interferometry permits the absolute measurement over the discontinued surface profiles while maintaining the sub-wavelength measurement precision.
doi:10.1117/12.2083260 fatcat:mwb4neatofavfmjn7xwikucaxa