Critical Dimension Calibration Standards for ULSI Metrology

Allen, Richard A.; Cresswell, Michael W.; Murabito, Christine E.; Dixson, Ronald G.; Bogardus, E. Hal

doi:10.1063/1.1622505

Cited by 10 publications

(11 citation statements)

References 8 publications

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“…These include serving as a reference tool for the CD-SEM benchmarking project 20,21 , metrology on photomasks, 193 nm resist shrinkage experiments 22 , and measurements on new NIST/ISMT linewidth standards. 23 In this section, we discuss the NIST/ISMT linewidth standards project in more detail.…”

Section: Applications Of the Rmsmentioning

confidence: 99%

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Reference metrology using a next-generation CD-AFM

Dixson

Guerry²

2004

Metrology, Inspection, and Process Control for Microlithography XVIII

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International SEMATECH (ISMT) and the National Institute of Standards and Technology (NIST) are working together to improve the traceability of AFM dimensional metrology in semiconductor manufacturing. Due to the unique metrology requirements and the rapid change in the semiconductor industry, relevant standards are often not available. Consequently, there is often no traceable linkage between the realization of the SI (Systeme International d'Unites, or International System of Units) unit of length -the meter -and measurements in the fab line. To improve this situation, we have implemented a Reference Measurement System (RMS) using a next-generation critical-dimension atomic force microscope (CD-AFM). We performed measurements needed to establish a traceability chain and developed uncertainty budgets for pitch, height, and critical dimension (CD) measurements. 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. Further improvement in these uncertainties is expected with the use of newer samples for scale and tip calibration. 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. As part of the NIST/ISMT linewidth standards project, we are performing an extensive comparison experiment of AFM and TEM (transmission electron microscopy) measurements of linewidth.

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Section: Applications Of the Rmsmentioning

confidence: 99%

“…[23][24][25] Our focus here is the role of CD-AFM in both the calibration and utilization of these samples. A new generation of these samples is currently being prepared and will soon be available.…”

Section: Nist/ismt Linewidth Standards Projectmentioning

confidence: 99%

Reference metrology using a next-generation CD-AFM

Dixson

Guerry²

2004

Metrology, Inspection, and Process Control for Microlithography XVIII

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“…[6][7][8] The current round of samples was released to SEMATECH Member Companies during October 2004. The SCCDRM features have nearvertical sidewalls; this is accomplished using preferential etching on {110} silicon-on-insulator (SOI) substrates.…”

Section: Application Of the Cd-afm Rms To The Sccdrm Projectmentioning

confidence: 99%

“…The background and history of this project has been described elsewhere. [6][7][8] Features on the SCCDRM samples are preferentially etched into a {110} silicon-on-insulator (SOI) substrate, so the sidewalls are near-vertical. Due to the crystalline nature of these features, it is possible to use the silicon lattice constant as a source of width information when the structures are measured using high resolution transmission electron microscopy (HRTEM).…”

Section: Introductionmentioning

confidence: 99%

CD-AFM reference metrology at NIST and SEMATECH

et al. 2005

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The National Institute of Standards and Technology (NIST) and SEMATECH have been working together to improve the traceability of critical dimension atomic force microscope (CD-AFM) dimensional metrology in semiconductor manufacturing. A major component of this collaboration has been the implementation of a Reference Measurement System (RMS) at SEMATECH using a current generation CD-AFM. An earlier tool, originally used at SEMATECH, has now been installed at NIST. Uncertainty budgets were developed for pitch, height, and CD measurements using both tools. At present, the standard uncertainties are approximately 0.2 % for pitch measurements and 0.4 % for step height measurements. Prior to the current work, CD-AFM linewidth measurements were limited to a standard uncertainty of about 5 nm. However, this limit can now be significantly reduced. This reduction results from the completion of the NIST/SEMATECH collaboration on the development of single crystal critical dimension reference materials (SCDDRM). A new generation of these reference materials was released to SEMATECH Member Companies during late 2004. The SEMATECH RMS was used to measure the linewidths of selected features on the distributed specimens. To reduce the uncertainty in tip width calibration, a separate transfer experiment was performed in which samples were measured by CD-AFM and then sent for high resolution transmission electron microscopy (HRTEM). In this manner, CD-AFM could be used to transfer the HRTEM width information to the distributed samples. Consequently, we are now able to reduce the limit on the standard uncertainty (k = 1) of CD-AFM width measurements to 1 nm.

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“…As a result of the NIST single crystal critical dimension reference material (SCCDRM) project, it is possible to calibrate CD-AFM tip width with a 1 nm standard uncertainty. 5,[11][12][13] And we are now using the SXM320 to support the next generation of the SCCDRM project, which may lead to even lower uncertainties.…”

Section: Introductionmentioning

confidence: 98%

Traceable atomic force microscope dimensional metrology at NIST

Dixson

Orji

et al. 2006

SPIE Proceedings

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The National Institute of Standards and Technology (NIST) has a multifaceted program in atomic force microscope (AFM) dimensional metrology. There are two major instruments being used for traceable AFM measurements at NIST. The first is a custom in-house metrology AFM, called the calibrated AFM (C-AFM), and the second instrument is a commercial critical dimension AFM (CD-AFM). The C-AFM has displacement metrology for all three axes traceable to the 633 nm wavelength of the Iodine-stabilized He-Ne laser. In the current generation of this system, the relative standard uncertainty of pitch and step height measurements is approximately 1.0 ×10 -3 for pitches at the micrometer scale and step heights at the 100 nm scale, as supported by several international comparisons. We expect to surpass this performance level soon. Since the CD-AFM has the capability of measuring vertical sidewalls, it complements the C-AFM. Although it does not have intrinsic traceability, it can be calibrated using standards measured on other instruments -such as the C-AFM, and we have developed uncertainty budgets for pitch, height, and linewidth measurements using this instrument. We use the CD-AFM primarily for linewidth measurements of near-vertical structures. At present, the relative standard uncertainties are approximately 0.2 % for pitch measurements and 0.4 % for step height measurements. As a result of the NIST single crystal critical dimension reference material (SCCDRM) project, it is possible to calibrate CD-AFM tip width with a 1 nm standard uncertainty. We are now using the CD-AFM to support the next generation of the SCCDRM project. In prototypes, we have observed features with widths as low as 20 nm and having uniformity at the 1 nm level.

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Critical Dimension Calibration Standards for ULSI Metrology

Cited by 10 publications

References 8 publications

Reference metrology using a next-generation CD-AFM

Reference metrology using a next-generation CD-AFM

CD-AFM reference metrology at NIST and SEMATECH

Traceable atomic force microscope dimensional metrology at NIST

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