Resist shrink characterization methodology for more accurate CD metrology

Breton, Mary; Petrillo, Karen; Church, Jennifer; Meli, Luciana; Fullam, Jennifer; Sieg, Stuart; Lallement, Romain; Felix, Nelson; Levi, Shimon; Zollinger, Susan; Levitov, Felix; Hand, Seán; Osborne, Jason A.; Wang, Weijie

doi:10.1117/12.2614219

Cited by 5 publications

(6 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although the benefit of moving to lower landing energy for reducing resist shrink is well studied [3,4], its effect on measured LWR is unknown. As the image contrast to noise ratio (CNR) is reduced while acquiring images with lower landing energies, there is a possibility that the measured LWR may change.…”

Section: Effect Of Landing Energy On Lwr Sensitivitymentioning

confidence: 99%

“…Typically, for EUV and resist layers in general, SEM scan conditions are optimized for best image contrast, SNR, shrink/damage reduction, and HVM considerations. In addition, recent work has shown the need for low-damage imaging enabled by low landing energy and low electron dose scanning regimes [3,4]. However, imaging under these conditions often yields lower contrast and higher noise than traditional imaging on After Etch Inspection (AEI) layers [2].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Unbiased roughness measurements for 0.55NA EUV material setup

Mathew

Arad

Brand

et al. 2023

Metrology, Inspection, and Process Control XXXVII

View full text Add to dashboard Cite

With the growing adoption of EUV lithography in both Logic and DRAM, the stochastics associated with EUV lithography has highlighted the need for accurate line roughness metrology. One of the approaches suggested to reduce stochastic effects is to transition to MOR (Metal Oxide Resist) from the traditional CAR resists. The CDSEM is the primary workhorse used today to measure line roughness in an inline environment. However, it is known that roughness reported by CD-SEM is dependent on the image acquisition conditions and the metrology algorithm settings. On the other hand, SEM metrology for EUV now requires low landing energies to minimize resist damage and increase contrast on thin high NA EUV resists [3]. However, this combination of low-dose scanning and low landing energies significantly lowers the contrast of the SEM image leading to higher reported roughness values using traditional roughness metrology algorithms. To understand and reduce the dependence of roughness on SEM image noise, we acquired images with different imaging conditions on a post-etch wafer and thin-resist EUV wafers with different stacks. The focus of this study is to demonstrate a novel roughness metrology algorithm that reduces the sensitivity of image SNR to roughness compared to traditional metrology methods. In this paper, we provide comprehensive guidelines for measuring unbiased roughness on thin EUV resist wafers in terms of roughness metrology and scanning conditions. We hope this work can provide the basis for understanding the roughness transfer from litho to etch and better characterize EUV lithography.

show abstract

Section: Effect Of Landing Energy On Lwr Sensitivitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Unbiased roughness measurements for 0.55NA EUV material setup

Mathew

Arad

Brand

et al. 2023

Metrology, Inspection, and Process Control XXXVII

View full text Add to dashboard Cite

show abstract

“…The SEM image reflects the shape information of the photoresist pattern after the original shape has been deformed. EB-induced shrinkage has been evaluated in previous works [8][9][10][11][12][13]. Measurement techniques that do not, in principle, cause EB-induced shrinkage, such as atomic force microscopy (AFM), are necessary for precise evaluation.…”

Section: Introductionmentioning

confidence: 99%

Photoresist shrinkage observation by a metrological tilting-AFM

Kizu

Misumi

Hirai

et al. 2023

Metrology, Inspection, and Process Control XXXVII

View full text Add to dashboard Cite

Scanning electron microscopy (SEM) is commonly used for line edge roughness (LER) measurement; however, it is difficult to achieve high-precision LER measurement of photoresists because exposure to an electron beam (EB) causes shrinkage of the materials. The differences in the 3D sidewall shape before and after shrinkage have not been investigated in detail. In this study, EB-induced photoresist shrinkage was observed by employing the atomic force microscopy with tip-tilting technique (tilting-AFM), which enables high-precision observation of the vertical sidewall of the pattern. In the experiment, the shrinkage deformation was observed by measuring the same photoresist pattern with the tilting-AFM before and after EB exposure (by SEM observation) on the pattern. The results show that the sidewall was smoothed by EB exposure. Further, the tendency of changes in LER (roughness parameters) was observed. This measurement technique can be used to better understand photoresist materials and to improve the LER measurement by SEM.

show abstract

“…EB-induced shrinkage has been evaluated in previous works 8 – 13 Measurement techniques that do not, in principle, cause EB-induced shrinkage, such as atomic force microscopy (AFM), are necessary for precise evaluation. An example of such a solution in CD measurement is reported in Ref.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the change in photoresist sidewall roughness due to electron beam-induced shrinkage using atomic force microscopy

Kizu,

Misumi,

Hirai

et al. 2023

J. Micro/Nanopattern. Mats. Metro.

View full text Add to dashboard Cite

.BackgroundScanning electron microscopy (SEM) is commonly employed for line edge roughness (LER) measurements; however, achieving high-precision LER measurement of photoresists is difficult through this approach because electron beam (EB) exposure causes shrinkage of materials. Moreover, the differences in the 3D sidewall shape before and after shrinkage have not been investigated in detail.AimEvaluation of the impact of photoresist shrinkage induced by EB exposure on the sidewall roughness of a pattern.ApproachThe shrinkage was observed by measuring a photoresist pattern before and after EB exposure using atomic force microscopy with a tip-tilting technique (tilting-AFM).ResultsEB exposure smoothed the surface roughness, rounded the top corners, and reduced the pattern height. Roughness parameters evaluated via LER analysis showed that with shrinkage, the standard deviation (σ) and roughness exponent (α) decreased, while the correlation length (ξ) increased.ConclusionsThe results show that SEM-based LER measurements may lead to underestimation of σ and α, and the overestimation of ξ because of the effect of EB-induced shrinkage. Overall, we establish a tilting-AFM technique to evaluate the 3D shape of photoresist patterns without EB damage and with high resolution and low noise.

show abstract

Resist shrink characterization methodology for more accurate CD metrology

Cited by 5 publications

References 0 publications

Unbiased roughness measurements for 0.55NA EUV material setup

Unbiased roughness measurements for 0.55NA EUV material setup

Photoresist shrinkage observation by a metrological tilting-AFM

Evaluation of the change in photoresist sidewall roughness due to electron beam-induced shrinkage using atomic force microscopy

Contact Info

Product

Resources

About