Implementation of Reference Measurement System using CD-AFM

International SEMATECH (ISMT) and the National Institute of Standards and Technology (NIST) are working together to improve the traceability of atomic force microscope (AFM) dimensional metrology in semiconductor manufacturing. The rapid pace of technological change in the semiconductor industry makes the timely introduction of relevant standards challenging. As a result, the link between the realization of the SI (Systeme International d’Unites, or International System of Units) unit of length - the meter - and measurements on the fab line is not always maintained. To improve this situation, we are using an at-line critical dimension-AFM (CD-AFM) at ISMT as a developmental platform. This tool has been implemented as a Reference Measurement System (RMS) in the facilities at ISMT. However, it is currently being replaced by a next-generation CD-AFM tool. Using the current tool, we have performed measurements needed to establish the traceability chain and developed uncertainty budgets. Specifically, we have developed uncertainty budgets for pitch, height, and critical dimension (CD) measurements. Some evaluations were performed using samples for which a full traceability chain is not available. We expect to improve the uncertainties further for such samples. At present, the standard uncertainties are estimated to be approximately 0.2 % for pitch measurements, 0.4 % for step height measurements, and 5 nm for CD measurements in the sub-micrometer range. Similar budgets will be developed for the new tool once it is installed. We will describe our methodology for RMS implementation and the major applications for which it has been used. These include measurements on new NIST/ISMT linewidth standards, a reference tool for CD-scanning electron microscopes (SEMs), metrology on photo-masks, CD-SEM benchmarking, and 193 nm resist shrinkage measurements.

[1]  Ronald G. Dixson,et al.  Improving Pitch and Step Height Measurements Using the Calibrated Atomic Force Microscope , 1998 .

[2]  Bhanwar Singh,et al.  Evaluation of atomic force microscopy: comparison with electrical CD metrology and low-voltage scanning electron microscopy , 1999, Advanced Lithography.

[3]  John S. Villarrubia,et al.  Strategy for faster blind reconstruction of tip geometry for scanned probe microscopy , 1998, Advanced Lithography.

[4]  Theodore V. Vorburger,et al.  Measurement of pitch and width samples with the NIST calibrated atomic force microscope , 1998, Advanced Lithography.

[5]  Herschel M. Marchman,et al.  AFM: a valid reference tool? , 1998, Advanced Lithography.

[6]  Scott E. Fuller,et al.  Photomask-edge-roughness characterization using an atomic force microscope , 1998, Advanced Lithography.

[7]  Mark Lagerquist,et al.  Improving SEM linewidth metrology by two-dimensional scanning force microscopy , 1996, Advanced Lithography.

[8]  Jeremiah R. Lowney,et al.  Scanning electron microscope analog of scatterometry , 2002, SPIE Advanced Lithography.

[9]  Samuel N. Jones,et al.  Interlaboratory Study on the Lithographically Produced Scanning Electron Microscope Magnification Standard Prototype , 1993, Journal of research of the National Institute of Standards and Technology.

[10]  Richard A. Allen,et al.  CD Reference Materials for Sub-Tenth Micrometer Applications , 2002 .

[11]  John Alexander,et al.  Design of an atomic force microscope with interferometric position control , 1994 .

[12]  Theodore V. Vorburger,et al.  Dimensional metrology with the NIST calibrated atomic force microscope , 1999, Advanced Lithography.

[13]  Ronald G. Dixson,et al.  Accurate dimensional metrology with atomic force microscopy , 2000, Advanced Lithography.

[14]  Nandasiri Samarakone,et al.  Quantitative line edge roughness characterization for sub-0.25-μm DUV lithography , 1999, Advanced Lithography.

[15]  Michael T. Postek,et al.  Toward traceability for at-line AFM dimensional metrology , 2002, SPIE Advanced Lithography.

[16]  J. Villarrubia.  Algorithms for Scanned Probe Microscope Image Simulation, Surface Reconstruction, and Tip Estimation , 1997, Journal of research of the National Institute of Standards and Technology.

[17]  H. Kumar Wickramasinghe,et al.  Method for imaging sidewalls by atomic force microscopy , 1994 .

[18]  James E. Potzick,et al.  Automated Calibration Of Optical Photomask Linewidth Standards At The National Institute Of Standards And Technology , 1989, Advanced Lithography.

[19]  Theodore V. Vorburger,et al.  Calibration of scanning electron microscope magnification standards SRM484 , 1996, Advanced Lithography.

[20]  T. V. Vorburger,et al.  The measurement and uncertainty of a calibration standard for the scanning electron microscope , 1994 .

[21]  J. Villarrubia.  Morphological estimation of tip geometry for scanned probe microscopy , 1994 .

[22]  Jeremiah R. Lowney,et al.  Edge determination for polycrystalline silicon lines on gate oxide , 2001, SPIE Advanced Lithography.

[23]  Charles N. Archie,et al.  Characteristics of accuracy for CD metrology , 1999, Advanced Lithography.

[24]  Ronald G. Dixson,et al.  Improving Step Height and Pitch Measurements Using the Calibrated Atomic Force Microscope , 1998 .

[25]  Barry N. Taylor,et al.  Guidelines for Evaluating and Expressing the Uncertainty of Nist Measurement Results , 2017 .