Influence of temperature on HSQ electron-beam lithography

Häffner, M.; Haug, Andrea; Heeren, A.; Fleischer, Monika; Peisert, Heiko; Chassé, Thomas; Kern, D. P.

doi:10.1116/1.2794324

Cited by 64 publications

(37 citation statements)

References 5 publications

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“…21 • C. The lithographic properties of HSQ are strongly influenced by elevated development temperatures, leading to a better contrast but a lower sensitivity. Dense lines and spaces have been successfully resolved using a temperature of 40 • C, 45 • C and 50 • C respectively [82][83][84]. In order to have good reproducibility, one should take care that the temperature is constant during the development process.…”

Section: Development Processmentioning

confidence: 99%

“…Dense lines with a pitch of 124 nm where successfully patterned at a dose of 185 μC cm −2 at 100 keV using xylenes as the developer for 60 s. Although the resolution is inferior compared with the one obtained with aqueous-based development, the optimization of the process can lead to better results. By using the assistance of ultrasonic agitation in the development, the thin scum between the dense lines is removed but the contrast is not significantly improved [83].…”

Section: Development Processmentioning

confidence: 99%

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Resists for sub-20-nm electron beam lithography with a focus on HSQ: state of the art

2009

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In the past decade, the feature size in ultra large-scale integration (ULSI) has been continuously decreasing, leading to nanostructure fabrication. Nowadays, various lithographic techniques ranging from conventional methods (e.g. photolithography, x-rays) to unconventional ones (e.g. nanoimprint lithography, self-assembled monolayers) are used to create small features. Among all these, resist-based electron beam lithography (EBL) seems to be the most suitable technique when nanostructures are desired. The achievement of sub-20-nm structures using EBL is a very sensitive process determined by various factors, starting with the choice of resist material and ending with the development process. After a short introduction to nanolithography, a framework for the nanofabrication process is presented. To obtain finer patterns, improvements of the material properties of the resist are very important. The present review gives an overview of the best resolution obtained with several types of both organic and inorganic resists. For each resist, the advantages and disadvantages are presented. Although very small features (2-5 nm) have been obtained with PMMA and inorganic metal halides, for the former resist the low etch resistance and instability of the pattern, and for the latter the delicate handling of the samples and the difficulties encountered in the spinning session, prevent the wider use of these e-beam resists in nanostructure fabrication. A relatively new e-beam resist, hydrogen silsesquioxane (HSQ), is very suitable when aiming for sub-20-nm resolution. The changes that this resist undergoes before, during and after electron beam exposure are discussed and the influence of various parameters (e.g. pre-baking, exposure dose, writing strategy, development process) on the resolution is presented. In general, high resolution can be obtained using ultrathin resist layers and when the exposure is performed at high acceleration voltages. Usually, one of the properties of the resist material is improved to the detriment of another. It has been demonstrated that aging, baking at low temperature, immediate exposure after spin coating, the use of a weak developer and development at a low temperature increase the sensitivity but decrease the contrast. The surface roughness is more pronounced at low exposure doses (high sensitivity) and high baking temperatures. A delay between exposure and development seems to increase both contrast and the sensitivity of samples which are stored in a vacuum after exposure, compared to those stored in air. Due to its relative novelty, the capabilities of HSQ have not been completely explored, hence there is still room for improvement.Applications of this electron beam resist in lithographic techniques other than EBL are also discussed. Finally, conclusions and an outlook are presented.

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Section: Development Processmentioning

confidence: 99%

Section: Development Processmentioning

confidence: 99%

Resists for sub-20-nm electron beam lithography with a focus on HSQ: state of the art

2009

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“…9 The insoluble layer is known to consist of siloxane-based network bonds, as confirmed by x-ray photoelectron spectroscopy and FTIR spectroscopy. 3,9 In order to analyze the change in chemical status during development, we carried out FTIR analysis by using annealed HSQ films.…”

Section: Results and Duscussionmentioning

confidence: 99%

“…2,3 Recently, a novel development system was reported by adding salt in hydroxide developers, which offers an outstanding ␥ value ͑ Ͼ 10͒ for high resolution and high density patterning. 4 Fundamental mechanisms of the cross-linking and development process of HSQ have been investigated in conventional pure hydroxide developer systems.…”

Section: Introductionmentioning

confidence: 99%

Contrast enhancement behavior of hydrogen silsesquioxane in a salty developer

Nam

Rooks

Yang

et al. 2009

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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The authors investigated a contrast enhancement behavior of hydrogen silsesquioxane ͑HSQ͒ in a salty development system ͑NaOH / NaCl͒. Time-resolved analysis of contrast curves and line-grating patterns were carried out to investigate the unique properties of a salty development process. In NaOH developer without salt, the development process was saturated beyond a certain development time. On the other hand, the addition of salt enabled a continuous development, which was not observed in the pure NaOH development. The continuous thinning process enhances the contrast of HSQ in the salty developer, which allows a fast collapsing behavior in HSQ line-grating patterns. During development process, salt seems to have the role of modifying HSQ by breaking network bonds preferentially, leading to a continuous development rate.

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“…Different resist film thicknesses of between 8 and 55 nm were achieved by varying the speed of the spinner ͑Karl Suss RC 5/8͒ and by diluting the HSQ resist with methyl isobutyl ketone. All resist films were dried for 30 min in vacuum at room temperature 5 to minimize film roughness. 4 Fine-line exposures in the FEI DB 235 system and the Raith eLine system were performed with the smallest probe size available, i.e., at 20 kV with beam currents of 16 and 14 pA and working distances of 5 and 10 mm, respectively.…”

Section: Methodsmentioning

confidence: 99%

Method for improving the aspect ratio of ultrahigh-resolution structures in negative electron-beam resist

Sidorkin

Alkemade

Salemink

et al. 2009

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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A method for improving the aspect ratio of ultrahigh-resolution structures in negative electron-beam resist is provided for enhanced pattern-transfer capabilities. The essence of the proposed method is to form a protective "cap" on top of the resist structure by means of electron-beam-induced deposition ͑EBID͒ in a self-aligned approach. This is implemented by a combination of electron-beam lithography and EBID during exposure of the resist material in the presence of a precursor gas. The results of the proposed method using hydrogen silsesquioxane resist material are presented and discussed, including various attempts to further optimize this method.

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Influence of temperature on HSQ electron-beam lithography

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Cited by 64 publications

References 5 publications

Resists for sub-20-nm electron beam lithography with a focus on HSQ: state of the art

Resists for sub-20-nm electron beam lithography with a focus on HSQ: state of the art

Contrast enhancement behavior of hydrogen silsesquioxane in a salty developer

Method for improving the aspect ratio of ultrahigh-resolution structures in negative electron-beam resist

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