Wavelength-multiplexed multi-mode EUV reflection ptychography based on automatic differentiation  

作　　者：Yifeng Shao Sven Weerdenburg Jacob Seifert H.Paul Urbach Allard P.Mosk Wim Coene 

机构地区：[1]Imaging Physics Department,Applied Science Faculty,Delft University of Technology,Lorentzweg 1,Delft 2628 CJ,The Netherlands [2]Nanophotonics,Debye Institute for Nanomaterials Science and Center for Extreme Matter and Emergent Phenomena,Utrecht University,P.0.Box 80000,Utrecht 3508 TA,The Netherlands [3]Research Department,ASML Netherlands B.V,De Run 6501,Veldhoven 5504DR,The Netherlands

出　　处：《Light(Science & Applications)》2024年第10期2156-2167,共12页光（科学与应用)（英文版）

基　　金：the project Lensless Imaging of 3D Nanostructures with Soft X-Rays(LINX)with project number P16-08 of the Perspectief research programme financed by the Dutch Research Council(NWO).

摘　　要：Ptychographic extreme ultraviolet(EUV)diffractive imaging has emerged as a promising candidate for the next generationmetrology solutions in the semiconductor industry,as it can image wafer samples in reflection geometry at the nanoscale.This technique has surged attention recently,owing to the significant progress in high-harmonic generation(HHG)EUV sources and advancements in both hardware and software for computation.In this study,a novel algorithm is introduced and tested,which enables wavelength-multiplexed reconstruction that enhances the measurement throughput and introduces data diversity,allowing the accurate characterisation of sample structures.To tackle the inherent instabilities of the HHG source,a modal approach was adopted,which represents the crossdensity function of the illumination by a series of mutually incoherent and independent spatial modes.The proposed algorithm was implemented on a mainstream machine learning platform,which leverages automatic differentiation to manage the drastic growth in model complexity and expedites the computation using GPU acceleration.By optimising over 2oo million parameters,we demonstrate the algorithm's capacity to accommodate experimental uncertainties and achieve a resolution approaching the diffraction limit in reflection geometry.The reconstruction of wafer samples with 20-nm high patterned gold structures on a silicon substrate highlights our ability to handle complex physical interrelations involving a multitude of parameters.These results establish ptychography as an efficient and accurate metrology tool.

关 键 词：metrology mode APPROACHING 

分 类 号：TN3[电子电信—物理电子学] O43[机械工程—光学工程]