Volume 32, Issue 3, May 2014
Index of content:
Actinic critical dimension measurement of contaminated extreme ultraviolet mask using coherent scattering microscopy32(2014); http://dx.doi.org/10.1116/1.4873697View Description Hide Description
The authors evaluated the feasibility of using coherent scattering microscopy (CSM) as an actinic metrology tool by employing it to determine the critical dimension (CD) and normalized image log-slope (NILS) values of contaminated extreme ultraviolet (EUV) masks. CSM was as effective as CD scanning electron microscopy (CD-SEM) in measuring the CD values of clean EUV masks in the case of vertical patterns (nonshadowing effect); however, only the CSM could detect shadowing effect for horizontal patterns resulting in smaller clear mask CD values. Owing to weak interaction between the low-density contaminant layer and EUV radiation, the CSM-based CD measurements were not as affected by contamination as were those made using CD-SEM. Furthermore, CSM could be used to determine the NILS values under illumination conditions corresponding to a high-volume manufacturing tool.
Efficient proximity effect correction method based on multivariate adaptive regression splines for grayscale e-beam lithography32(2014); http://dx.doi.org/10.1116/1.4875955View Description Hide Description
Grayscale electron beam lithography is an important technique to manufacture three-dimensional (3D) micro- and nano-structures, such as diffractive optical devices and Fresnel lenses. However, the proximity effect due to the scattering of electrons may cause significant error to the desired 3D structure. Conventional proximity correction methods depend on the exposure energy distribution which sometimes is difficult to obtain. In this study, the authors develop a novel proximity effect correction method based on multivariate adaptive regression splines, which takes exposure energy and development into consideration simultaneously. To evaluate the method, a Fresnel lens was fabricated through simulation and experiment. The measurements demonstrate the feasibility and validity of the method.