Contrast optimization for 0.33NA EUV lithography

Finders, Jo; Wuister, Sander F.; Rispens, Gijsbert; Psari, Eleni; Lubkoll, Jan; Setten, Eelco van; Wittebrood, Friso

doi:10.1117/12.2220036

Cited by 15 publications

(13 citation statements)

References 1 publication

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“…As the focus of this work is on resist properties, the aerial image properties are kept constant. The LCDU can of course be further improved by increasing optical contrast through pupil optimization and increasing the numerical aperture, [8][9][10] but this is considered out of scope for this work.…”

Section: Introductionmentioning

confidence: 99%

Stochastics in extreme ultraviolet lithography: investigating the role of microscopic resist properties for metal-oxide-based resists

Maas

Lare

Rispens

et al. 2018

J. Micro/Nanolith. MEMS MOEMS

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Due to the high energy of extreme ultraviolet (EUV) photons, stochastic effects become more important at a constant dose when compared with deep ultraviolet exposures. Photoresists are used to transfer information from the aerial image into physical features and play an important role in the transduction of these stochastic effects. Recently, metal-oxide-based nonchemically amplified resists (non-CARs) have attracted a lot of attention. We study how the properties of these non-CARs impact the local critical dimension uniformity (LCDU) of a regular contact hole array printed with EUV lithography using Monte Carlo simulations and an analytical model. We benchmark both the simulations and the analytical model to experimental data, and then use the flexibility of both methods to systematically investigate the role of microscopic resist properties in the final LCDU. It is found that metal-oxide clusters should be <1 nm in diameter, otherwise granularity will have a significant contribution to LCDU. When varying resist properties to change the resist dose-to-size, we find that the LCDU scaling with dose depends on how the resist is modified. After performing an overall sensitivity analysis to identify the optimum scaling of LCDU with dose, we find a scaling of dose −0.5 when the development threshold is modified, and a scaling of dose −0.33 when core radius or the quantum efficiency is changed.

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Section: Introductionmentioning

confidence: 99%

Stochastics in extreme ultraviolet lithography: investigating the role of microscopic resist properties for metal-oxide-based resists

Maas

Lare

Rispens

et al. 2018

J. Micro/Nanolith. MEMS MOEMS

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“…In section 3 compensate f the impact is g more and m g [20]. The first idea is to scale the current concept by adding more motors to deliver the required forces.…”

Section: Mask Stamentioning

confidence: 99%

EUV high-NA scanner and mask optimization for sub-8nm resolution

Jan¹,

Koen²,

Bottiglieri³

et al. 2016

Extreme Ultraviolet (EUV) Lithography VII

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EUV lithography for resolution below 8 nm half pitch requires the numerical aperture (NA) of the projection lens to be significantly larger than the current state-of-the-art 0.33NA. In order to be economically viable, a throughput in the range of 100 wafers per hour is needed.As a result of the increased NA, the incidence angles of the light rays at the mask increase significantly. Consequently the shadowing and the variation of the multi-layer reflectivity deteriorate the aerial image contrast to unacceptably low values at the current 4x magnification.The only solution to reduce the angular range at the mask is to increase the magnification. Simulations show that we have to double the magnification to 8x in order to overcome the shadowing effects. Assuming that the mask infrastructure will not change the mask form factor, this would inevitably lead to a field size that is a quarter of the field size of current 0.33NA step & scan systems. This would reduce the throughput of the high-NA scanner to a value significantly below 100 wafers per hour unless additional measures are taken. This paper presents an anamorphic step & scan system capable to print fields that are half the field size of the current full field. The anamorphic system has the potential to achieve a throughput in excess of 150 wafers per hour by increasing the transmission of the optics as well as increasing the acceleration of the wafer stage and mask stage. This makes it an economically viable lithography solution.The proposed 4x/8x magnification is not the only logical solution. There are potentially other magnifications to increase the scanner performance while at the same time reducing the mask requirements.

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“…Measuring LCDU and plotting vs 1/NILS 18 shows the strong dependency of LCDU on image contrast. As shown in Fig.…”

Section: Lcdu and Lcdu Modelmentioning

confidence: 99%

“…Finders et al 18 showed that illumination mode can be adjusted to provide highest contrast. High aerial image contrast is essential to have high quality patterns, with lower roughness and lower dose.…”

Section: Contrast Improvementmentioning

confidence: 99%

Improvements in resist performance towards EUV HVM

et al. 2017

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Extreme ultraviolet (EUV) lithography with 13.5 nm wavelength is the main option for sub-10nm patterning in the semiconductor industry. We report improvements in resist performance towards EUV high volume manufacturing. A local CD uniformity (LCDU) model is introduced and validated with experimental contact hole (CH) data. Resist performance is analyzed in terms of ultimate printing resolution (R), line width roughness (LWR), sensitivity (S), exposure latitude (EL) and depth of focus (DOF). Resist performance of dense lines at 13 nm half-pitch and beyond is shown by chemical amplified resist (CAR) and non-CAR (Inpria YA Series) on NXE scanner. Resolution down to 10nm half pitch (hp) is shown by Inpria YA Series resist exposed on interference lithography at the Paul Sherrer Institute. Contact holes contrast and consequent LCDU improvement is achieved on a NXE:3400 scanner by decreasing the pupil fill ratio. State-of-the-art imaging meets 5nm node requirements for CHs. A dynamic gas lock (DGL) membrane is introduced between projection optics box (POB) and wafer stage. The DGL membrane will suppress the negative impact of resist outgassing on the projection optics by 100%, enabling a wider range of resist materials to be used. The validated LCDU model indicates that the imaging requirements of the 3nm node can be met with single exposure using a high-NA EUV scanner. The current status, trends, and potential roadblocks for EUV resists are discussed. Our results mark the progress and the improvement points in EUV resist materials to support EUV ecosystem.

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Contrast optimization for 0.33NA EUV lithography

Cited by 15 publications

References 1 publication

Stochastics in extreme ultraviolet lithography: investigating the role of microscopic resist properties for metal-oxide-based resists

Stochastics in extreme ultraviolet lithography: investigating the role of microscopic resist properties for metal-oxide-based resists

EUV high-NA scanner and mask optimization for sub-8nm resolution

Improvements in resist performance towards EUV HVM

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