Dr. Ndubuisi G. Orji Profile

Dr. Ndubuisi G. Orji

Mechanical Engineer at National Institute of Standards and Technology

SPIE Involvement:

Conference Program Committee | Conference Co-Chair | Conference Chair | Author | Editor

Publications (46)

SPIE Journal Paper | June 19, 2017

Multiple-instrument evaluation of the consistency and long-term stability of tip width calibration for critical dimension atomic force microscopy

Dixson, Ronald , Orji, Ndubuisi

JM3 Vol. 16 Issue 02

KEYWORDS: Calibration, Standards development, Atomic force microscopy, Atomic force microscope, Metrology, Contamination, Electron microscopes

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SPIE Journal Paper | December 15, 2016

Contour metrology using critical dimension atomic force microscopy

Orji, Ndubuisi , Dixson, Ronald , Ng, Boon Ping , Vladár, András , Postek, Michael

JM3 Vol. 15 Issue 04

KEYWORDS: Metrology, Scanning electron microscopy, Atomic force microscopy, Error analysis, Calibration, 3D metrology, Image segmentation, Optical proximity correction, Lithography, Composites

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SPIE Journal Paper | October 13, 2016

Transmission electron microscope calibration methods for critical dimension standards

Orji, Ndubuisi G. , Dixson, Ronald , Garcia-Gutierrez, Domingo , Bunday, Benjamin , Bishop, Michael , Cresswell, Michael , Allen, Richard , Allgair, John A.

JM3 Vol. 15 Issue 04

KEYWORDS: Critical dimension metrology, Calibration, Transmission electron microscopy, Electron microscopes, Error analysis, Silicon, Line width roughness, Oxides, Statistical analysis, Standards development

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SPIE Journal Paper | August 26, 2016

Evaluation of carbon nanotube probes in critical dimension atomic force microscopes

Choi, Jinho , Park, Byong Chon , Ahn, Sang Jung , Kim, Dal-Hyun , Lyou, Joon , Dixson, Ronald , Orji, Ndubuisi , Fu, Joseph , Vorburger, Theodore

JM3 Vol. 15 Issue 03

KEYWORDS: Scanning electron microscopy, Line edge roughness, Carbon nanotubes, Atomic force microscope, Metrology, Atomic force microscopy, Standards development, Silicon, Manufacturing, Ion beams

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SPIE Journal Paper | March 9, 2016

Process optimization for lattice-selective wet etching of crystalline silicon structures

Dixson, Ronald , Guthrie, William , Allen, Richard , Orji, Ndubuisi , Cresswell, Michael , Murabito, Christine

JM3 Vol. 15 Issue 01

KEYWORDS: Etching, Silicon, Calibration, Crystals, Standards development, Scanning electron microscopy, Oxides, Metrology, Wet etching, Photomasks

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SPIE Journal Paper | January 25, 2016

Lateral tip control effects in critical dimension atomic force microscope metrology: the large tip limit

Dixson, Ronald , Orji, Ndubuisi , Goldband, Ryan

JM3 Vol. 15 Issue 01

KEYWORDS: Virtual point source, Atomic force microscope, Calibration, Metrology, Critical dimension metrology, Standards development, Atomic force microscopy, Silicon, Semiconductor manufacturing, Statistical modeling

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Sidewall sensing in critical dimension atomic force microscopes (CD-AFMs) usually involves continuous lateral dithering of the tip or the use of a control algorithm and fast response piezoactuator to position the tip in a manner that resembles touch-triggering of coordinate measuring machine probes. All methods of tip position control, however, induce an effective tip width that may deviate from the actual geometrical tip width. Understanding the influence and dependence of the effective tip width on the dither settings and lateral stiffness of the tip can improve the measurement accuracy and uncertainty estimation for CD-AFM measurements. Since CD-AFM typically uses tips that range from 15 to 850 nm in geometrical width, the behavior of effective tip width throughout this range should be understood. The National Institute of Standards and Technology (NIST) has been investigating the dependence of effective tip width on the dither settings and lateral stiffness of the tip, as well as the possibility of material effects due to sample composition. For tip widths of 130 nm and lower, which also have lower lateral stiffness, the response of the effective tip width to lateral dither is greater than for larger tips. However, we have concluded that these effects will not generally result in a residual bias, provided that the tip calibration and sample measurement are performed under the same conditions. To confirm that our prior conclusions about the dependence of effective tip width on lateral stiffness are valid for large CD tips, we recently performed experiments using a very large non-CD tip with an etched plateau of ∼2-μm width. The effective lateral stiffness of these tips is at least 20 times greater than typical CD-AFM tips, and these results supported our prior conclusions about the expected behavior for larger tips. The bottom-line importance of these latest observations is that we can now reasonably conclude that a dither slope of 3 nm/V is the baseline response due to the induced motion of the cantilever base.

PROCEEDINGS ARTICLE | October 21, 2015

Lateral tip control effects in CD-AFM metrology: the large tip limit

Proc. SPIE. 9636, Scanning Microscopies 2015

KEYWORDS: Actuators, Metrology, Calibration, Silicon, Physics, Atomic force microscopy, Virtual point source, Atomic force microscope, Critical dimension metrology, Standards development

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SPIE Conference Volume | September 10, 2014

Instrumentation, Metrology, and Standards for Nanomanufacturing, Optics, and Semiconductors VIII

PROCEEDINGS ARTICLE | September 8, 2014

Technique for AFM tip characterization

Proc. SPIE. 9173, Instrumentation, Metrology, and Standards for Nanomanufacturing, Optics, and Semiconductors VIII

KEYWORDS: Semiconductors, Metrology, Calibration, Silicon, Atomic force microscopy, Transmission electron microscopy, Atomic force microscope, Critical dimension metrology, Photomicroscopy, System on a chip

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SPIE Conference Volume | September 25, 2013

Instrumentation, Metrology, and Standards for Nanomanufacturing, Optics, and Semiconductors VII

SPIE Journal Paper | June 4, 2013

Distributed force probe bending model of critical dimension atomic force microscopy bias

Ukraintsev, Vladimir , Orji, Ndubuisi , Vorburger, Theodore , Dixson, Ronald , Fu, Joseph , Silver, Richard

JM3 Vol. 12 Issue 02

KEYWORDS: Atomic force microscopy, Data modeling, 3D modeling, Numerical analysis, Error analysis, Metrology, Statistical modeling, Carbon nanotubes, Solids, Standards development

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PROCEEDINGS ARTICLE | April 18, 2013

TSV reveal height and dimension metrology by the TSOM method

Proc. SPIE. 8681, Metrology, Inspection, and Process Control for Microlithography XXVII

KEYWORDS: Metrology, 3D acquisition, Etching, Copper, Silicon, Optical microscopy, Inspection, Interferometry, Semiconducting wafers, Diffusion tensor imaging

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This paper reports on an investigation to determine whether through-focus scanning optical microscopy (TSOM) is applicable to micrometer-scale through-silicon via (TSV) reveal metrology. TSOM has shown promise as an alternative inspection and dimensional metrology technique for FinFETs and defects. In this paper TSOM measurements were simulated using 546 nm light and applied to copper TSV reveal pillars with height in the 3 μm to 5 μm range and diameter of 5 μm. Simulation results, combined with white light interferometric profilometry, are used in an attempt to correlate TSOM image features to variations in TSV height, diameter, and sidewall angle (SWA). Simulations illustrate the sensitivity of Differential TSOM Images (DTI’s) using the metric of Optical Intensity Range (OIR), for 5 μm diameter and 5 μm height TSV Cu reveal structures, for variation of SWA (Δ = 2°, OIR = 2.35), height (Δ = 20 nm, OIR = 0.28), and diameter (Δ = 40 nm, OIR = 0.57), compared to an OIR noise floor of 0.01. In addition, white light interferometric profilometry reference data is obtained on multiple TSV reveal structures in adjacent die, and averages calculated for each die’s SWA, height, and diameter. TSOM images are obtained on individual TSV’s within each set, with DTI’s obtained by comparing TSV’s from adjacent die. The TSOM DTI’s are compared to average profilometry data from identical die to determine whether there are correlations between DTI and profilometry data. However, with several significant TSV reveal features not accounted for in the simulation model, it is difficult to draw conclusions comparing profilometry measurements to TSOM DTI’s when such features generate strong optical interactions. Thus, even for similar DTI images there are no discernible correlations to SWA, diameter, or height evident in the profilometry data. The use of a more controlled set of test structures may be advantageous in correlating TSOM to optical images.

SPIE Conference Volume | October 19, 2012

Instrumentation, Metrology, and Standards for Nanomanufacturing, Optics, and Semiconductors VI

SPIE Journal Paper | May 29, 2012

Robust auto-alignment technique for orientation-dependent etching of nanostructures

McGray, Craig , Orji, Ndubuisi , Dixson, Ronald , Cresswell, Michael , Allen, Richard , Geist, Jon , Kasica, Richard

JM3 Vol. 11 Issue 02

KEYWORDS: Etching, Crystals, Nanostructures, Photomasks, Silicon, Nanolithography, Lithography, Optical alignment, Atomic force microscopy, Semiconducting wafers

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PROCEEDINGS ARTICLE | May 14, 2012

Progress on CD-AFM tip width calibration standards

Proc. SPIE. 8378, Scanning Microscopies 2012: Advanced Microscopy Technologies for Defense, Homeland Security, Forensic, Life, Environmental, and Industrial Sciences

KEYWORDS: Nanotechnology, Electron beam lithography, Metrology, Calibration, Etching, Crystals, Silicon, Line width roughness, Nanolithography, Standards development

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PROCEEDINGS ARTICLE | April 3, 2012

On CD-AFM bias related to probe bending

Proc. SPIE. 8324, Metrology, Inspection, and Process Control for Microlithography XXVI

KEYWORDS: Semiconductors, Metrology, Statistical analysis, Data modeling, 3D modeling, Atomic force microscopy, Numerical analysis, 3D metrology, Statistical modeling, Standards development

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PROCEEDINGS ARTICLE | April 3, 2012

Contour metrology using critical dimension atomic force microscopy

Proc. SPIE. 8324, Metrology, Inspection, and Process Control for Microlithography XXVI

KEYWORDS: Lithography, Metrology, Electron microscopes, Atomic force microscopy, Scanning electron microscopy, Scanning helium ion microscopy, Data acquisition, 3D metrology, Atomic force microscope, Optical proximity correction

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SPIE Journal Paper | March 8, 2012

Traceable calibration of a critical dimension atomic force microscope

Dixson, Ronald , Orji, Ndubuisi , McGray, Craig , Bonevich, John , Geist, Jon

JM3 Vol. 11 Issue 1

KEYWORDS: Calibration, Atomic force microscopy, Atomic force microscope, Standards development, Transmission electron microscopy, Crystals, Metrology, Semiconductor manufacturing, Dimensional metrology, Nanotechnology

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SPIE Journal Paper | February 24, 2012

Dimensional Metrology with Atomic Force Microscopy

Dixson, Ronald , Orji, Ndubuisi

JM3 Vol. 11 Issue 1

KEYWORDS: Atomic force microscopy, Dimensional metrology, Metrology, Microscopy, Analytical research, Biological research, Materials science, Cell biology, Nanostructures, Interferometry

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PROCEEDINGS ARTICLE | September 20, 2011

Strategies for nanoscale contour metrology using critical dimension atomic force microscopy

Proc. SPIE. 8105, Instrumentation, Metrology, and Standards for Nanomanufacturing, Optics, and Semiconductors V

KEYWORDS: Lithography, Metrology, Error analysis, Feature extraction, Atomic force microscopy, Scanning electron microscopy, Data acquisition, 3D metrology, Optical proximity correction, Resolution enhancement technologies

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PROCEEDINGS ARTICLE | June 1, 2011

Traceable calibration of a critical dimension atomic force microscope

Proc. SPIE. 8036, Scanning Microscopies 2011: Advanced Microscopy Technologies for Defense, Homeland Security, Forensic, Life, Environmental, and Industrial Sciences

KEYWORDS: Nanotechnology, Metrology, Calibration, Crystals, Atomic force microscopy, Dimensional metrology, Atomic force microscope, Semiconductor manufacturing, Helium neon lasers, Standards development

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SPIE Journal Paper | January 1, 2011

Multilaboratory comparison of traceable atomic force microscope measurements of a 70-nm grating pitch standard

Dixson, Ronald , Chernoff, Donald , Wang, Shihua , Vorburger, Theodore , Tan, Siew-Leng , Orji, Ndubuisi , Fu, Joseph

JM3 Vol. 10 Issue 1

KEYWORDS: Calibration, Metrology, Atomic force microscope, Atomic force microscopy, Standards development, Error analysis, Interferometry, Scanners, Interferometers, Helium neon lasers

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SPIE Journal Paper | January 1, 2011

Measurement traceability and quality assurance in a nanomanufacturing environment

Orji, Ndubuisi , Dixson, Ronald , Cordes, Aaron , Bunday, Benjamin , Allgair, John

JM3 Vol. 10 Issue 1

KEYWORDS: Metrology, Calibration, Environmental sensing, Quality measurement, Manufacturing, Control systems, Data processing, Standards development, Measurement devices, Error analysis

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PROCEEDINGS ARTICLE | June 10, 2010

Interlaboratory comparison of traceable atomic force microscope pitch measurements

Proc. SPIE. 7729, Scanning Microscopy 2010

KEYWORDS: Metrology, Interferometers, Calibration, Scanners, Error analysis, Atomic force microscopy, Head, Atomic force microscope, Helium neon lasers, Standards development

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PROCEEDINGS ARTICLE | April 2, 2010

Calibration of 1-nm SiC step height standards

Proc. SPIE. 7638, Metrology, Inspection, and Process Control for Microlithography XXIV

KEYWORDS: Calibration, Etching, Error analysis, Crystals, Atomic force microscopy, Capacitance, Atomic force microscope, Silicon carbide, Motion measurement, Standards development

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PROCEEDINGS ARTICLE | September 23, 2009

Results of an international photomask linewidth comparison of NIST and PTB

Proc. SPIE. 7488, Photomask Technology 2009

KEYWORDS: Microscopes, Metrology, Calibration, Ultraviolet radiation, Microscopy, Atomic force microscopy, Scanning electron microscopy, Photomasks, Critical dimension metrology, Standards development

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PROCEEDINGS ARTICLE | August 21, 2009

Measurement traceability and quality assurance in a nanomanufacturing environment

Proc. SPIE. 7405, Instrumentation, Metrology, and Standards for Nanomanufacturing III

KEYWORDS: Metrology, Calibration, Error analysis, Manufacturing, Control systems, Quality measurement, Time metrology, Data processing, Measurement devices, Environmental sensing

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PROCEEDINGS ARTICLE | March 23, 2009

Reference metrology in a research fab: the NIST clean calibrations thrust

Proc. SPIE. 7272, Metrology, Inspection, and Process Control for Microlithography XXIII

KEYWORDS: Semiconductors, Nanotechnology, Metrology, Calibration, Scanners, Atomic force microscopy, Scanning electron microscopy, Profiling, Dimensional metrology, Standards development

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PROCEEDINGS ARTICLE | March 23, 2009

Through-focus scanning and scatterfield optical methods for advanced overlay target analysis

Proc. SPIE. 7272, Metrology, Inspection, and Process Control for Microlithography XXIII

KEYWORDS: Optical microscopes, Polarization, Calibration, Microscopy, Silicon, Reflectivity, Optical testing, Scatterometry, Optical aberrations, Overlay metrology

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PROCEEDINGS ARTICLE | October 17, 2008

Re-calibration of the NIST SRM 2059 master standard using traceable atomic force microscope metrology

Proc. SPIE. 7122, Photomask Technology 2008

KEYWORDS: Microscopes, Metrology, Calibration, Ultraviolet radiation, Atomic force microscopy, Optical testing, Dimensional metrology, Photomasks, Atomic force microscope, Standards development

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PROCEEDINGS ARTICLE | September 9, 2008

Accuracy considerations for critical dimension semiconductor metrology

Proc. SPIE. 7042, Instrumentation, Metrology, and Standards for Nanomanufacturing II

KEYWORDS: Semiconductors, Lithography, Metrology, Calibration, Atomic force microscopy, Transmission electron microscopy, Atomic force microscope, Line edge roughness, Standards development, Carbon nanotubes

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PROCEEDINGS ARTICLE | March 24, 2008

Characterization of CD-SEM metrology for iArF photoresist materials

Proc. SPIE. 6922, Metrology, Inspection, and Process Control for Microlithography XXII

KEYWORDS: Lithography, Metrology, Roentgenium, Cadmium, Atomic force microscopy, Scanning electron microscopy, Photoresist materials, Extreme ultraviolet, Critical dimension metrology, Semiconducting wafers

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PROCEEDINGS ARTICLE | March 22, 2008

Toward accurate feature shape metrology

Proc. SPIE. 6922, Metrology, Inspection, and Process Control for Microlithography XXII

KEYWORDS: Metrology, Calibration, Electron microscopes, Feature extraction, Atomic force microscopy, Transmission electron microscopy, Head, Process control, Atomic force microscope, Binary data

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PROCEEDINGS ARTICLE | October 30, 2007

Photomask applications of traceable atomic force microscope dimensional metrology at NIST

Proc. SPIE. 6730, Photomask Technology 2007

KEYWORDS: Metrology, Calibration, Resistance, Atomic force microscopy, Dimensional metrology, Microelectronics, Photomasks, Atomic force microscope, Standards development, Phase shifts

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The National Institute of Standards and Technology (NIST) has a multifaceted program in atomic force microscope (AFM) dimensional metrology. Three major instruments are being used for traceable measurements. The first is a custom in-house metrology AFM, called the calibrated AFM (C-AFM), the second is the first generation of commercially available critical dimension AFM (CD-AFM), and the third is a current generation CD-AFM at SEMATECH - for which NIST has established the calibration and uncertainties. All of these instruments have useful applications in photomask metrology. Linewidth reference metrology is an important application of CD-AFM. We have performed a preliminary comparison of linewidths measured by CD-AFM and by electrical resistance metrology on a binary mask. For the ten selected test structures with on-mask linewidths between 350 nm and 600 nm, most of the observed differences were less than 5 nm, and all of them were less than 10 nm. The offsets were often within the estimated uncertainties of the AFM measurements, without accounting for the effect of linewidth roughness or the uncertainties of electrical measurements. The most recent release of the NIST photomask standard - which is Standard Reference Material (SRM) 2059 - was also supported by CD-AFM reference measurements. We review the recent advances in AFM linewidth metrology that will reduce the uncertainty of AFM measurements on this and future generations of the NIST photomask standard. The NIST C-AFM has displacement metrology for all three axes traceable to the 633 nm wavelength of the iodine-stabilized He-Ne laser. One of the important applications of the C-AFM is step height metrology, which has some relevance to phase shift calibration. In the current generation of the system, the approximate level of relative standard uncertainty for step height measurements at the 100 nm scale is 0.1 %. We discuss the monitor history of a 290 nm step height, originally measured on the C-AFM with a 1.9 nm (k = 2) expanded uncertainty, and describe advances that bring the step height uncertainty of recent measurements to an estimated 0.6 nm (k = 2). Based on this work, we expect to be able to reduce the topographic component of phase uncertainty in alternating aperture phase shift masks (AAPSM) by a factor of three compared to current calibrations based on earlier generation step height references.

PROCEEDINGS ARTICLE | April 5, 2007

TEM calibration methods for critical dimension standards

Proc. SPIE. 6518, Metrology, Inspection, and Process Control for Microlithography XXI

KEYWORDS: Metrology, Calibration, Crystals, Silicon, Image resolution, Electron microscopes, Scanning electron microscopy, Transmission electron microscopy, Atomic force microscope, Standards development

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One of the key challenges in critical dimension (CD) metrology is finding suitable calibration standards. Over the last few years there has been some interest in using features measured with the transmission electron microscope (TEM) as primary standards for linewidth measurements. This is because some modes of TEM can produce lattice-resolved images having scale traceability to the SI (Systeme International d'Unites or International System of Units) definition of length through an atomic lattice constant. As interest in using calibration samples that are closer to the length scales being measured increases, so will the use of these TEM techniques. An area where lattice-traceable images produced by TEM has been used as a primary standard is in critical dimension atomic force microscope (CD-AFM) tip width calibration. Two modes of TEM that produce crystal lattice-traceable images are high resolution transmission electron microscope (HR-TEM) and high angle annular dark field scanning transmission electron microscope (HAADF-STEM). HR-TEM produces lattice-traceable images by interference patterns of the diffracted and transmitted beams rather than the actual atomic columns, while HAADF-STEM produces direct images of the crystal lattice. The difference in how both of these techniques work could cause subtle variations in the way feature edges are defined. In this paper, we present results from width samples measured using HR-TEM and HAADF-STEM. Next we compare the results with measurements taken from the same location by two different CD-AFMs. Both of the CD-AFM instruments used for this work have been calibrated using a single crystal critical dimension reference material (SCCDRM). These standards, developed by the National Institute of Standards and Technology (NIST) and SEMATECH, used HR-TEM for traceable tip-width calibration. Consequently, the present work and the previous SCCDRM work provide a mutual cross-check on the traceability of the width calibration. Excellent agreement was observed.

PROCEEDINGS ARTICLE | April 5, 2007

The coming of age of tilt CD-SEM

Proc. SPIE. 6518, Metrology, Inspection, and Process Control for Microlithography XXI

KEYWORDS: Lithography, Metrology, Calibration, Scanners, Scanning electron microscopy, Photoresist materials, Process control, Critical dimension metrology, Semiconducting wafers, Fin field effect transitor

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The need for 3D metrology is becoming more urgent to address critical gaps in metrology for both lithographic and etch processes. Current generation lithographic processing (ArF source, where λ=193 nm) sometimes results in photoresist lines with re-entrant profiles or T-topping, as do many etch processes. A re-entrant profile misleads top-down metrology into reading the critical dimension (CD) as too large. Recent advances in gate process technology also raise challenges to traditional top-down metrology. One such example is the FinFET, which is truly a 3D device with 3D metrology needs. The ability to measure the bottom width of a profile is crucial for process control. Recently, tilt-beam critical dimension-scanning electron microscopy (CD-SEM) applications have been developed to measure the bottom CD of such features, using the tilted-view to "see" the bottom, avoiding the feature's larger top. This is an important achievement, as the bottom of a profile is the main feature of interest in many processes. Estimation of sidewall angle (SWA) is also important. For several years, tilt-beam CD-SEM has been an available technique for this measurement, with limited adoption by the litho-metrology community. However, in this paper we will explore another method to use the tilt feature to measure average sidewall angle, based on edgewidth measurement and the assumption of basic trapezoidal profile and known height and combined with the ability to sample multiple-features. While it will not provide exact profile shape, this technique can be quite useful in providing average profile information and will definitely exhibit good throughput. Samples used will be photoresist and etched FinFET structures to measure sidewall angles. Correlations of the results to a traceable CD-atomic force microscopy (AFM) reference measurement system are provided. Conclusions will show preliminary findings of the readiness of tilt-beam CD-SEM for measuring profile and, by extension, the status of measuring 3D structures such as FinFETs, and using CD-SEM as a direct control of lithographic tooling for T-topped photoresist profiles.

PROCEEDINGS ARTICLE | April 5, 2007

Single crystal critical dimension reference materials (SCCDRM): process optimization for the next generation of standards

Proc. SPIE. 6518, Metrology, Inspection, and Process Control for Microlithography XXI

KEYWORDS: Oxides, Metrology, Calibration, Etching, Silicon, Atomic force microscopy, Ultrasonics, Scanning electron microscopy, Photomasks, Standards development

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PROCEEDINGS ARTICLE | April 5, 2007

Comparison and uncertainties of standards for critical dimension atomic force microscope tip width calibration

Proc. SPIE. 6518, Metrology, Inspection, and Process Control for Microlithography XXI

KEYWORDS: Metrology, Calibration, Etching, Silicon, Scanning electron microscopy, Transmission electron microscopy, Line width roughness, Atomic force microscope, Charge-coupled devices, Standards development

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PROCEEDINGS ARTICLE | April 5, 2007

Application of carbon nanotube probes in a critical dimension atomic force microscope

Proc. SPIE. 6518, Metrology, Inspection, and Process Control for Microlithography XXI

KEYWORDS: Metrology, Silicon, Platinum, Atomic force microscopy, Scanning electron microscopy, Ion beams, Atomic force microscope, Line edge roughness, Standards development, Carbon nanotubes

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SPIE Journal Paper | April 1, 2007

Progress on implementation of a reference measurement system based on a critical-dimension atomic force microscope

Orji, Ndubuisi , Dixson, Ronald , Martinez, Angela , Bunday, Benjamin , Allgair, John , Vorburger, Theodore

JM3 Vol. 6 Issue 02

KEYWORDS: Calibration, Standards development, Error analysis, Scanners, Atomic force microscope, Silicon, Semiconductor manufacturing, Semiconductors, Metrology, Semiconducting wafers

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PROCEEDINGS ARTICLE | March 24, 2006

Litho-metrology challenges for the 45-nm technology node and beyond

Proc. SPIE. 6152, Metrology, Inspection, and Process Control for Microlithography XX

KEYWORDS: Amorphous silicon, Lithography, Reticles, Metrology, Calibration, Manufacturing, Scanning electron microscopy, Critical dimension metrology, Semiconducting wafers, Overlay metrology

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PROCEEDINGS ARTICLE | March 24, 2006

Traceable atomic force microscope dimensional metrology at NIST

Proc. SPIE. 6152, Metrology, Inspection, and Process Control for Microlithography XX

KEYWORDS: Metrology, Calibration, Error analysis, Crystals, Atomic force microscopy, Dimensional metrology, Photomasks, Atomic force microscope, Prototyping, Standards development

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PROCEEDINGS ARTICLE | March 24, 2006

Progress on implementation of a CD-AFM-based reference measurement system

Proc. SPIE. 6152, Metrology, Inspection, and Process Control for Microlithography XX

KEYWORDS: Semiconductors, Metrology, Calibration, Scanners, Error analysis, Silicon, Dimensional metrology, Atomic force microscope, Standards development, Liquid crystal lasers

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PROCEEDINGS ARTICLE | May 24, 2004

Determination of optimal parameters for CD-SEM measurement of line-edge roughness

Proc. SPIE. 5375, Metrology, Inspection, and Process Control for Microlithography XVIII

KEYWORDS: Edge detection, Metrology, Image segmentation, Image quality, Line width roughness, Critical dimension metrology, Line edge roughness, Tolerancing, Edge roughness, Line scan image sensors

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The measurement of line-edge roughness (LER) has recently become a topic of concern in the litho-metrology community and the semiconductor industry as a whole. The Advanced Metrology Advisory Group (AMAG), a council composed of the chief metrologists from the International SEMATECH (ISMT) consortium’s Member Companies and from the National Institute of Standards and Technology (NIST), has a project to investigate LER metrics and to direct the critical dimension scanning electron microscope (CD-SEM) supplier community towards a semiconductor industry-backed, standardized solution for implementation. The 2003 International Technology Roadmap for Semiconductors (ITRS) has included a new definition for roughness. The ITRS envisions root mean square measurements of edge and width roughness. There are other possible metrics, some of which are surveyed here. The ITRS envisions the root mean square measurements restricted to roughness wavelengths falling within a specified process-relevant range and with measurement repeatability better than a specified tolerance. This study addresses the measurement choices required to meet those specifications. An expression for the length of line that must be measured and the spacing of measurement positions along that length is derived. Noise in the image is shown to produce roughness measurement errors that have both random and nonrandom (i.e., bias) components. Measurements are reported on both UV resist and polycrystalline silicon in special test patterns with roughness typical for those materials. These measurements indicate that the sensitivity of a roughness measurement to noise depends importantly both on the choice of edge detection algorithm and the quality of the focus. Measurements are less sensitive to noise when a model-based or sigmoidal fit algorithm is used and when the images are in good focus. Using the measured roughness characteristics for UV resist lines and applying the ITRS requirements for the 90 nm technology node, the derived expression for sampling length and sampling interval implies that a length at least 8 times the node (i.e., 720 nm) must be measured at intervals of 7.5 nm or less.

PROCEEDINGS ARTICLE | June 2, 2003

Subnanometer wavelength metrology of lithographically prepared structures: a comparison of neutron and X-ray scattering

Proc. SPIE. 5038, Metrology, Inspection, and Process Control for Microlithography XVII

KEYWORDS: Diffraction, Metrology, Scattering, X-rays, Light scattering, Atomic force microscopy, Scanning electron microscopy, Photoresist materials, Scatterometry, X-ray lithography

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PROCEEDINGS ARTICLE | August 22, 2001

Silicon single atom steps as AFM height standards

Proc. SPIE. 4344, Metrology, Inspection, and Process Control for Microlithography XV

KEYWORDS: Oxides, Metrology, Statistical analysis, Calibration, Chemical species, Error analysis, Silicon, Atomic force microscopy, Atomic force microscope, Standards development

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