193-nm CD shrinkage under SEM: modeling the mechanism

Habermas, Andrew; Hong, D.; Ross, Matthew F.; Livesay, William R.

doi:10.1117/12.473436

Cited by 36 publications

(54 citation statements)

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“…For advanced logic processes 5 nm consumes the entire process tolerance. Using this AFM data to describe the dependence of resist slimming on landing energy, as Habermas 11 has done for long term (many repeats) data, results in observed behavior which is much closer to the V 1.75 landing energy dependence predicted by the Grün range expression. This may suggest that the conceptual view of line slimming as arising from separate mechanisms (as depicted in the triple exponential model), has significant merit.…”

Section: Discussionsupporting

confidence: 64%

“…It seems clear from the foregoing experimental results as well as from work performed by other researchers, 8,9,10,11,12 that for the preponderance of 193 nm resist formulations, control over landing energy is essential to minimize the resist slimming effect. The results indicate that the linewidth slimming effect is dependent upon the landing energy, which is directly related to the penetration depth of the incident electrons.…”

Section: Discussionmentioning

confidence: 87%

“…8,9,10,11 Several potential solutions have been proposed, including reformulation of resist to withstand electron beam exposure 9 and pre-dosing samples until the trending levels off. 8 Vasconi, et al found that "Electron landing energy is the key parameter to minimize the resist CD variation amplitude".…”

Section: Introductionmentioning

confidence: 99%

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Electron beam metrology of 193-nm resists at ultralow voltage

Sullivan

Dixson

Bunday³

et al. 2003

SPIE Proceedings

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Resist slimming under electron beam exposure introduces significant measurement uncertainty in the metrology of 193 nm resists. Total critical dimension (CD) uncertainty of up to 10 nm can arise from line slimming through a combination of the line slimming during the initial measurement pass and the variation of line slimming across the wafer. For a 100 nm process, the entire CD error budget, can be consumed by line slimming. This research examines the uncertainty that results from the use of offset techniques to account for resist slimming in the process control of 193 nm resist CDs. The uncertainty associated with such offset techniques can be as great as 10 nm, depending upon the 193 nm resist and landing energy evaluated. Data are presented to demonstrate that 193 nm resist CD features experience line slimming greater than 5 nm at 500 eV landing energy during the initial measurement pass. Further, subsequent measurements demonstrate greatly reduced slimming and as a result are not indicative of the true magnitude of line slimming. Experiments conducted using CD-AFM pre-and post-analysis, demonstrate that ultra low landing energies significantly decrease the line slimming, reducing it to 1 nm or less.

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Section: Discussionsupporting

confidence: 64%

Section: Discussionmentioning

confidence: 87%

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Electron beam metrology of 193-nm resists at ultralow voltage

Sullivan

Dixson

Bunday³

et al. 2003

SPIE Proceedings

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“…The magnitude of the difference is consistent with previously observed shrinkage rates. 15,16 The methods had a random difference with standard deviation of 5 nm, 3 nm of which is expected from the observed linewidth roughness.…”

Section: Tests Of the Approach Accuracymentioning

confidence: 99%

Scanning electron microscope dimensional metrology using a model‐based library

Villarrubia

Vladár

Postek

2005

Surface & Interface Analysis

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The semiconductor electronics industry places significant demands upon secondary electron imaging to obtain dimensional measurements that are used for process control or failure analysis. Tolerances for measurement uncertainty and repeatability are smaller than the spatial resolution of edges in the scanning electron microscope (SEM) that is used to perform the measurements. Image processing techniques, historically used to identify edge locations, are inadequate under these conditions. An alternative approach, based upon Monte Carlo electron transport modeling to assign edge positions, has been developed. The specimen shape is parameterized, and parameters are iteratively adjusted to produce the best least squares fit to the measured image. Because Monte Carlo simulators are too slow to be used directly in such an iterative calculation, the Monte Carlo technique is used relatively few times to construct a library of results for parameters spanning the process space of interest. A function that interpolates the library then becomes a surrogate that is used to rapidly compute the model function as needed. This procedure has yielded measurement results from top-down SEM images that are in good agreement with cross-section measurements and that have as much as a factor of 3 better same-site repeatability than the more traditional techniques. Published in 2005 by John Wiley & Sons, Ltd.

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“…However, a continuing outstanding issue is discerning and measuring material changes caused by the shrinkage. It is theorized that resist shrinkage is mostly caused by the loss of ester groups liberated by the beam energy, which then escape the material [3]. This should lead both to a hardening of the material, and reduction in hydrophilic activity, among other changes that may potentially have consequences on advanced processing outside the purely dimensional changes.…”

Section: Introductionmentioning

confidence: 99%

Quantitative nanomechanical measurement of electron beam surface modification

Cordes¹,

Bunday²,

Montgomery³

et al. 2015

SPIE Proceedings

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Electron beam induced surface damage in general, and resist shrinkage in particular, are serious issues in any form of electron beam based metrology. Previous studies investigated dimensional changes that occur in resists that were exposed to electron beams. This work builds on these previous studies to consider changes to the material properties of the exposed resists and other materials using quantitative nano-mechanical mapping scanning probe microscopy. Initial data has shown clearly that there are measurable material differences between pre-and post-electron beam exposure. To study this change iArF photo-resists are exposed to varying electron beam energies and doses. These regions are then measured via SPM for dimensional and material property changes. These changes in the exposed areas are correlated to those predicted by modeled results.

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193-nm CD shrinkage under SEM: modeling the mechanism

Cited by 36 publications

References 0 publications

Electron beam metrology of 193-nm resists at ultralow voltage

Electron beam metrology of 193-nm resists at ultralow voltage

Scanning electron microscope dimensional metrology using a model‐based library

Quantitative nanomechanical measurement of electron beam surface modification

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