Photoresist Shrinkage Caused by Single-Line Scan of Electron Beam

Ohashi, T.; Tanaka, J.

doi:10.1143/jjap.51.06fb10

Cited by 4 publications

(5 citation statements)

References 31 publications

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“…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

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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.

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Section: Introductionmentioning

confidence: 99%

Photoresist shrinkage observation by a metrological tilting-AFM

Kizu

Misumi

Hirai

et al. 2023

Metrology, Inspection, and Process Control XXXVII

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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.

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.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.

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“…The problem is well-known as the shrinkage of photoresist, which may cause a systematic error during a measurement. Most of the works on resist shrinkage have been about photoresist materials, such as 193-nm resist, which have been widely using in industry [1][2][3][4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

“…Because of the fact that to collect the signal for an SEM image, there is always an EB irradiated on the sample, that makes SEM inspection very challenging to acquire the original sizes of patterns [3]. T. Ohashi et al used only a single-line scan of EB to minimise the shrinkage, but it is far from a typical SEM measurement [4].…”

Section: Introductionmentioning

confidence: 99%

Electron-Beam Induced Shrinkage Effects on Line-Space Patterns of ZEP Resist

Dinh

Oshima

Nishijima

et al. 2016

J. Photopol. Sci. Technol.

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ZEP resist patterns, which have been widely used in nanofabrication in research laboratories, are shrunk during an SEM observation. This shrinkage effect makes it challenging to accurately determine their original sizes. In this work, the shrinkage effect of electron beams on ZEP resist line-space patterns was explored by AFM measurement at different exposure doses. The results shown that the shrinkage happened at doses as low as 0.05 mC/cm 2 , and dramatically increased before being saturated at high doses of 16 -24 mC/cm 2 (at 30 keV). For patterns with the same height, a smaller pattern tended to undergo a bigger shrinkage. The heights of patterns also had a great impact on their shrinkages. In the saturation region at high does, the patterns were unchanged in isopropyl alcohol developer. The insolubility of the patterns suggested that the resist had changed to a negative tone, where the number of crosslinking sites of the resist was high, and caused the saturation of shrinkage. A new method for estimating of the original size was also introduced using a combination of SEM, EB exposure, and AFM.

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Photoresist Shrinkage Caused by Single-Line Scan of Electron Beam

Cited by 4 publications

References 31 publications

Photoresist shrinkage observation by a metrological tilting-AFM

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

Electron-Beam Induced Shrinkage Effects on Line-Space Patterns of ZEP Resist

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