Photochemical conversion of tin-oxo cage compounds studied using hard x-ray photoelectron spectroscopy

Haitjema, Jarich; Liu, Xiaomeng; Johansson, Fredrik; Lindblad, Andreas; Castellanos, Sonia; Ottosson, Niklas; Brouwer, Albert M.

doi:10.1117/1.jmm.16.2.023510

Cited by 39 publications

(65 citation statements)

References 29 publications

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“…1,3 It is generally accepted that the metallic atoms absorb a large fraction of the EUV light 7,8 while reactions of the organic parts are responsible for the solubility switching properties. [9][10][11][12] A particular mechanism that illustrates this distinction of the roles of organic and inorganic components in hybrid photoresists was proposed for the well-known Inpria type of nonchemically amplified resists, where the insolubility of the exposed areas arise from ligand cleavage and inorganic core aggregation. 13 In addition, the inorganic components in the photoresist provide the final patterns with good mechanical and chemical stability.…”

Section: Introductionmentioning

confidence: 99%

Mechanistic insights in Zr- and Hf-based molecular hybrid EUV photoresists

Baljozović

Portale

et al. 2019

J. Micro/Nanolith. MEMS MOEMS

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Background: Inorganic resists show promising performances in extreme ultraviolet (EUV) lithography. Yet, there is a need for understanding the exact chemical mechanisms induced by EUV light on these materials. Aim: To gain knowledge on the EUV chemistry of inorganic resists, we investigate hybrid inorganic-organic molecular compounds, metal oxoclusters (MOCs). Their molecular nature allows for the monitoring of specific structural changes by means of spectroscopy and thus for the elucidation of the mechanisms behind pattern formation. Approach: We compare the sensitivity of MOCs based on Zr and Hf, and methacrylate ligands as EUV resists. The chemical and structural changes causing the solubility switch were investigated by ex situ x-ray spectroscopy, infrared spectroscopy, ultraviolet-visible spectroscopy, and grazing incidence x-ray scattering. Results: Higher sensitivity was detected for the Hf-based material, in line with its higher absorptivity. A small fraction of the carboxylate ligands is lost at doses that yield solubility contrast, whereas aggregation of the inorganic clusters was not observed. Conclusions: These results provide evidence that, although the mechanism of solubility switch in these materials starts with decarboxylation reactions, it mainly proceeds through cross linking of the organic shells instead of aggregation of the inorganic clusters.

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Section: Introductionmentioning

confidence: 99%

Mechanistic insights in Zr- and Hf-based molecular hybrid EUV photoresists

Baljozović

Portale

et al. 2019

J. Micro/Nanolith. MEMS MOEMS

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“…This is likely due to loss of more of the butyl chains, in analogy to the results of deep UV exposures. 16 In addition to the anion effect, improvements to the process can also alter the contrast curves. In fact, photoresist parameters such as sensitivity and resolution are only meaningful concepts if the process conditions are optimized.…”

Section: Open-frame Experiments: Contrast Curvesmentioning

confidence: 99%

“…The chemical changes upon exposure to short-wavelength UV light are discussed elsewhere. 16,17 2 Materials and Methods…”

Section: Introductionmentioning

confidence: 99%

Extreme ultraviolet patterning of tin-oxo cages

Haitjema

Vockenhuber

Kazazis

et al. 2017

J. Micro/Nanolith. MEMS MOEMS

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Abstract. We report on the extreme ultraviolet (EUV) patterning performance of tin-oxo cages. These cage molecules were already known to function as a negative tone photoresist for EUV radiation, but in this work, we significantly optimized their performance. Our results show that sensitivity and resolution are only meaningful photoresist parameters if the process conditions are optimized. We focus on contrast curves of the materials using large area EUV exposures and patterning of the cages using EUV interference lithography. It is shown that baking steps, such as postexposure baking, can significantly affect both the sensitivity and contrast in the open-frame experiments as well as the patterning experiments. A layer thickness increase reduced the necessary dose to induce a solubility change but decreased the patterning quality. The patterning experiments were affected by minor changes in processing conditions such as an increased rinsing time. In addition, we show that the anions of the cage can influence the sensitivity and quality of the patterning, probably through their effect on physical properties of the materials.

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“…The patterning performance of these materials at EUV have been recently studied and show a good potential for high resolution and high sensitivity 16 . In addition, the chemical changes upon DUV exposure were studied for these materials and a chemical mechanism for the observed changes was proposed 17 . One commercial zirconium oxocluster (ZrM1) was purchased from Sigma-Aldrich (CAS 189028-53-3) and used as isaside from the dilution rate which was tuned.…”

Section: Experimental Details 21 Transmittance Measurement At the XImentioning

confidence: 99%

Absorption coefficient and exposure kinetics of photoresists at EUV

Fallica

Haitjema

et al. 2017

SPIE Proceedings

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The experimental measurement of the time-dependent absorption of photoresists at extreme ultraviolet wavelength is of great interest for the modeling of the lithographic process. So far, several technical challenges have made the accurate determination of the linear absorption coefficient and the Dill parameters nontrivial. In this work, we use a dedicated equipment and synchrotron light source to experimentally measure the transmittance of thin layers of photoresists on transparent silicon nitride membranes, and their thickness was measured with the spectroscopic ellipsometry. The absorption of negative tone photocondensed metal oxide photoresists based on Sn cage structures, and of Zr and Hf oxoclusters was measured and compared to the estimated values. It was found that tin based materials absorb considerably more light than conventional chemically amplified resists based on organic polymer. Hafnium-based materials have about twice absorption, while zirconium based are basically comparable to organic resists. Furthermore, the exposure kinetics of several chemically amplified resists with varying photoacid concentration and backbone polymer was studied. The rate of bleaching, described by the Dill parameter C, was measured and conclusions are drawn based on the specific resist formulation.

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Photochemical conversion of tin-oxo cage compounds studied using hard x-ray photoelectron spectroscopy

Cited by 39 publications

References 29 publications

Mechanistic insights in Zr- and Hf-based molecular hybrid EUV photoresists

Mechanistic insights in Zr- and Hf-based molecular hybrid EUV photoresists

Extreme ultraviolet patterning of tin-oxo cages

Absorption coefficient and exposure kinetics of photoresists at EUV

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