Challenges in line edge roughness metrology in directed self-assembly lithography: placement errors and cross-line correlations

Constantoudis, Vassilios; Papavieros, George; Gogolides, Εvangelos; Pret, Alessandro Vaglio; Pathangi, Hari; Gronheid, Roel

doi:10.1117/1.jmm.16.2.024001

Cited by 11 publications

(12 citation statements)

References 14 publications

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“…Here, c is the c-factor quantifying the cross-correlations between the left and right edges of lines. For totally uncorrelated edges, c = 0, whereas for fully correlated (anti-correlated), c = 1 (−1) [26,33]. By combining (2), (3), and (4) we read:σ(Α)=2〈CDi〉 (1−c)false(rmsLER2(total)−<rmsLER2(CDifalse)>).…”

Section: Resultsmentioning

confidence: 99%

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Impact of Line Edge Roughness on ReRAM Uniformity and Scaling

et al. 2019

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We investigate the effects of Line Edge Roughness (LER) of electrode lines on the uniformity of Resistive Random Access Memory (ReRAM) device areas in cross-point architectures. To this end, a modeling approach is implemented based on the generation of 2D cross-point patterns with predefined and controlled LER and pattern parameters. The aim is to evaluate the significance of LER in the variability of device areas and their performances and to pinpoint the most critical parameters and conditions. It is found that conventional LER parameters may induce >10% area variability depending on pattern dimensions and cross edge/line correlations. Increased edge correlations in lines such as those that appeared in Double Patterning and Directed Self-assembly Lithography techniques lead to reduced area variability. Finally, a theoretical formula is derived to explain the numerical dependencies of the modeling method.

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Section: Resultsmentioning

confidence: 99%

“…Furthermore, it was recently realized that LER characteristics are sensitive to the applied lithographic technique [33]. The main point of differentiation comes from the degree of correlations between the fabricated edges and lines.…”

Section: Introductionmentioning

confidence: 99%

Impact of Line Edge Roughness on ReRAM Uniformity and Scaling

et al. 2019

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“…In the case of diblock copolymer directed self-assembly, even measurement of line-edge roughness presents a new challenge. 19 A more difficult question is whether or not the self-assembly process, can be controlled sufficiently well to avoid defects. 20–26 As a first step, it is important to be able to see defects in what are predominantly soft-material systems.…”

Section: Directed Self-assemblymentioning

confidence: 99%

Research Update: Electron beam-based metrology after CMOS

et al. 2018

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The magnitudes of the challenges facing electron-based metrology for post-CMOS technology are reviewed. Directed selfassembly, nanophotonics/plasmonics, and resistive switches and selectors, are examined as exemplars of important post-CMOS technologies. Materials, devices, and architectures emerging from these technologies pose new metrology requirements: defect detection, possibly subsurface, in soft materials, accurate measurement of size, shape, and roughness of structures for nanophotonic devices, contamination-free measurement of surface-sensitive structures, and identification of subtle structural, chemical, or electronic changes of state associated with switching in non-volatile memory elements. Electron-beam techniques are examined in the light of these emerging requirements. The strong electron-matter interaction provides measurable signal from small sample features, rendering electron-beam methods more suitable than most for nanometer-scale metrology, but as is to be expected, solutions to many of the measurement challenges are yet to be demonstrated. The seeds of possible solutions are identified when they are available.

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“…This range exceeds correlation lengths measured of DSA patterns on chemically templated substrates, in which correlations are limited by the three-fold periodicity of the underlying guide pattern. 26 While edge correlations are consistently positive, the intensity of correlations between adjacent cylinders is observed to modulate between alternating edges: Edges that span PMMA domains (e i,L → e i,R ) show a stronger correlation than those across PS domains (e i,R → e i+1,L ). The effect is most apparent when examining the adjacent off-diagonal terms in Figure 6a at 150 °C.…”

mentioning

confidence: 97%

“…56 This methodology follows a procedure employed by Constantoudis et al to describe cross-line correlations in DSA-templated patterns. 26 Similar definitions may be used to compare cylinder widths and placements. This approach allows us to measure the extent of lateral correlation across a trench based on PCC values ranging from −1 (negative correlation) to 1 (positive correlation).…”

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confidence: 99%

Direct Imaging of Interfacial Fluctuations in Confined Block Copolymer with in Situ Slow-Scan-Disabled Atomic Force Microscopy

et al. 2019

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Using environmentally controlled, high-speed atomic force microscopy (AFM), we examine dynamic fluctuations of topographically confined poly(styrene-block-methyl methacrylate) (PS-b-PMMA) cylinders. During thermal annealing, fluctuations drive perturbations of the block copolymer (BCP) interface between polymer domains, leading to pattern roughness. Whereas previous investigations have examined roughness in room-temperature and kinetically quenched samples, we directly visualize the dynamics of PS/PMMA interfaces in real space and time at in situ temperatures above the glass transition temperature, T g. Imaging under these experimentally challenging thermal annealing conditions is critical to understanding the inherent connection between thermal fluctuations and BCP pattern assembly. Through the use of slow-scan-disabled AFM, we dramatically improve the imaging time resolution for tracking polymer dynamics. Fluctuations increase in intensity with temperature and, at high temperatures, become spatially coherent across their confining potential. Additionally, we observe that topographic confinement suppresses fluctuations and correlations in the proximity of the guiding field. In situ imaging at annealing temperatures represents a significant step in capturing the dynamics of chain mobility at BCP interfaces.

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Challenges in line edge roughness metrology in directed self-assembly lithography: placement errors and cross-line correlations

Cited by 11 publications

References 14 publications

Impact of Line Edge Roughness on ReRAM Uniformity and Scaling

Impact of Line Edge Roughness on ReRAM Uniformity and Scaling

Research Update: Electron beam-based metrology after CMOS

Direct Imaging of Interfacial Fluctuations in Confined Block Copolymer with in Situ Slow-Scan-Disabled Atomic Force Microscopy

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