Angular scatterometry for line-width roughness measurement

Abstract

We propose using angular scatterometry as a means to investigate LWR (line-width roughness) and CD (critical dimension). The grating target is illuminated by a single wavelength light source which has large angular aperture both in incidence angle θ and azimuth angle φ . A preliminary scatterometry model was first built by assuming perfect critical dimension printed without any line-width roughness. The difference between the model prediction and actual measurement is cased by line-width roughness contribution. We developed a calibration curve as a function of line-width roughness based on the statistical quantity of the incidence and azimuth angle dependence. The results demonstrate that scatterometry can indeed be used to extract line-width roughness and critical dimension information in production line with nano-scale resolution.

Sidewall roughness in nanolithography: origins, metrology and device effects

“…Other approaches employ dark-fi eld scatterometry, ellipsometry, angular resolved scatterometry, etc. (Brill et al ., 2010;Foldyna et al ., 2011;Shyu et al ., 2007). Modeling studies have also been performed, testing new techniques in simulating the effects of LER on scattered light such as the fi eld-stitching method (Schuster et al ., 2009).…”

Effects of vertical sidewall roughness on near-UV biosensing nanoresonant gratings

“…Mathematical characterization of the roughness in this way during the manufacturing process is a really important aspect of production, and it is convenient to note the roughness at which the specifications are exceeded, which can be judged to be a failure under quality control. This quality control then can be conducted by using scatterometry and RCWA to identify the spectral reflectance [17]. The procedure is summarized in figure 8(e).…”

“…However, the current scale of the short wavelength is closer to that of the roughness than infrared (IR) wavelengths; hence, the effects of roughness can be intuitively inferred to be more pronounced in the short wavelength regime. Line-edge roughness and surface roughness are known vital issues as the line width of nanotechnology advances toward only a few tens of nanometers for both electronics and photonics [16][17][18][19][20]. Roughness cannot be scaled down as the line width shrinks, and this results in a high electrical threshold voltage and variations in current leakage [16,17,21].…”

“…Line-edge roughness and surface roughness are known vital issues as the line width of nanotechnology advances toward only a few tens of nanometers for both electronics and photonics [16][17][18][19][20]. Roughness cannot be scaled down as the line width shrinks, and this results in a high electrical threshold voltage and variations in current leakage [16,17,21]. In addition, the roughness degrades the sensitivity of the nanophotonic elements that are required to achieve highly integrated optoelectronic circuits for versatile applications [19,20,22].…”

Fast characterization of moving samples with nano-textured surfaces

“…Several types of scatterometers exist, including ODM [2,4,3], angular scatterometry [5,6,7], Fourier lens system [8], coherent Fourier scatterometry [9,10,11], white light interference Fourier scatterometry [12], and naked-eye observations [13]. Two general challenges for scatterometry are imaging of small areas and finding a specific area of interest.…”