Specular spectroscopic scatterometry in DUV lithography

Niu, Xinhui; Jakatdar, Nickhil H.; Bao, Junwei Lucas; Spanos, Costas J.; Yedur, Sanjay

doi:10.1117/12.350802

Cited by 44 publications

(21 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This step is often referred to as the solution of the forward problem. Rigorous coupled-wave analysis (RCWA) 7,8,9,10,11 , which is still widely used, is limited to gratings consisting of stacks of rectangular structures. We use the finite element method (FEM) 12,13,14,15,16 which allows the modeling of arbitrarily shaped structures and for potentially higher accuracy as compared to the RCWA method 17 .…”

Section: Introductionmentioning

confidence: 99%

Comparison of CD measurements of an EUV photomask by EUV scatterometry and CD-AFM

et al. 2013

View full text Add to dashboard Cite

EUV scatterometry is a potential high-throughput measurement method for the characterization of EUV photomask structures. We present a comparison of angle resolved extreme ultraviolet (EUV) scatterometry and critical dimension atomic force microscope (CD-AFM) as a reference metrology for measurements of geometrical parameters like line width (CD), height and sidewall angle of EUV photomask structures. The structures investigated are dense and semidense bright and dark lines with different nominal CDs between 140 nm and 540 nm. The results show excellent linearity of the critical dimension measured with both methods within a range of only 1.8 nm and an offset of the absolute values below 3 nm. A maximum likelihood estimation (MLE) method is used to reconstruct the shape parameters and to estimate their uncertainties from the measured scattering efficiencies. The newly developed CD-AFM at PTB allows versatile measurements of parameters such as height, CD, sidewall angle, line edge/width roughness, corner rounding, and pitch. It applies flared tips to probe steep and even undercut sidewalls and employs a new vector approaching probing (VAP) strategy which enables very low tip wear and high measurement flexibility. Its traceability is ensured by a set of calibrated step-height and reference CD standards.

show abstract

Section: Introductionmentioning

confidence: 99%

Comparison of CD measurements of an EUV photomask by EUV scatterometry and CD-AFM

et al. 2013

View full text Add to dashboard Cite

show abstract

“…A new possibility is the combination of the two methods, 23 although ellipsometry has already been used for scattering or diffracting samples in specular or normal-incidence configurations. [24][25][26][27] The high speed of optical methods can also be utilized in large area mapping of thin film properties, 2, 3, 28 e.g. photovoltaic 29 or display panels.…”

Section: Optical Methodsmentioning

confidence: 99%

Methods for optical modeling and cross-checking in ellipsometry and scatterometry

et al. 2015

View full text Add to dashboard Cite

Indirect optical methods like ellipsometry or scatterometry require an optical model to calculate the response of the system, and to fit the parameters in order to minimize the difference between the calculated and measured values. The most common problem of optical modeling is that the measured structures and materials turn out to be more complex in reality than the simplified optical models used as first attempts to fit the measurement. The complexity of the optical models can be increased by introducing additional parameters, if they (1) are physically relevant, (2) improve the fit quality, (3) don't correlate with other parameters. The sensitivity of the parameters can be determined by mathematical analysis, but the accuracy has to be validated by reference methods. In this work some modeling and verification aspects of ellipsometry and optical scatterometry will be discussed and shown for a range of materials (semiconductors, dielectrics, composite materials), structures (damage and porosity profiles, gratings and other photonic structures, surface roughness) and cross-checking methods (atomic force microscopy, electron microscopy, x-ray diffraction, ion beam analysis). The high-sensitivity, high-throughput, in situ or in line capabilities of the optical methods will be demonstrated by different applications.

show abstract

“…Different methods are applied such as spectroscopic ellipsometry [1,2], normal incidence reflectometry [3], 2-9-scatterometry [4] or angular resolved Fourier scatterometry [5]. A quite comprehensive overview about different techniques is given by Raymond [6,7].…”

Section: Introductionmentioning

confidence: 99%

Simulations of Scatterometry Down to 22 nm Structure Sizes and Beyond with Special Emphasis on LER

Paz¹,

Frenner²,

Schuster³

et al. 2009

AIP Conference Proceedings

View full text Add to dashboard Cite

Abstract. In recent years, scatterometry has become one of the most commonly used methods for CD metrology. With decreasmg structure size for future technology nodes, the search for optimized scatterometry measurement configurations gets more important to exploit maximum sensitivity. As widespread industrial scatterometry tools mainly still use a pre-set measurement configuration, there are still free parameters to improve sensitivity. Our current work uses a simulation based approach to predict and optimize sensitivity of future technology nodes. Since line edge roughness is getting important for such small structures, these imperfections of the periodic continuation cannot be neglected. Using fourier methods like e.g. rigorous coupled wave approach (RCWA) for diffraction calculus, nonperiodic features are hard to reach. We show that in this field certain types of fieldstitching methods show nice numerical behaviour and lead to useful results.

show abstract

Specular spectroscopic scatterometry in DUV lithography

Cited by 44 publications

References 2 publications

Comparison of CD measurements of an EUV photomask by EUV scatterometry and CD-AFM

Comparison of CD measurements of an EUV photomask by EUV scatterometry and CD-AFM

Methods for optical modeling and cross-checking in ellipsometry and scatterometry

Simulations of Scatterometry Down to 22 nm Structure Sizes and Beyond with Special Emphasis on LER

Contact Info

Product

Resources

About