Newsletter_04-2024_EN

Advances in processes, masks and metrology will enable to fully benefit
from the resolution gain offered by the first ASML 0.55NA EUV scanner
Imec demonstrates readiness of the
High-NA EUV patterning ecosystem
Field stitching is a key enabler in High-NA: field stitching is needed
because of the anamorphic lens (i.e., a lens with different de-magnification
in the x and y directions), resulting in field sizes of half of the
conventional scanner field size. Imec will share the latest insights
that enable at-resolution stitching based on work done with ASML
and our mask shop partners on imec’s NXE:3400C scanner. At-resolution
stitching will reduce the need for design changes to cope
with the field size reduction.
Assembly of a High NA EUV tool in joint imec-ASML High-NA lab at
ASML’s headquarters in Veldhoven, the Netherlands. (Credit: ASML)
This week, at the 2024 Advanced Lithography + Patterning Conference,
imec, a world-leading research and innovation hub in nanoelectronics
and digital technologies, will present the progress made in
EUV processes, masks, and metrology prepared for enabling highnumerical
aperture (High-NA) extreme ultraviolet (EUV) lithography.
Key achievements are reported on resist and underlayer development,
mask enhancement, optical proximity correction (OPC)
development, at-resolution field stitching, reduction of stochastic
failures, and improved metrology and inspection. With these results,
imec demonstrates readiness for transferring the EUV processes
into the joint imec-ASML High-NA EUV Lab, built around the first
prototype High-NA EUV scanner.
Steven Scheer, senior vice president of Advanced Patterning, Process
and Materials at imec: “The first High-NA EUV scanner (TWIN-
SCAN EXE:5000) has been assembled by ASML and the first wafers
will be exposed soon. In the next few months, the joint imec-ASML
High-NA EUV Lab will be operational, and access will be provided
to the High-NA customers. The High-NA EUV lab, with the installed
equipment and processes, enables an early start of High-NA EUV
learning for the customers before tools are operational in their fabs.
It has been imec’s role, in tight collaboration with ASML and our extended
supplier network, to ensure timely availability of advanced
resist materials, photomasks, metrology techniques, (anamorphic)
imaging strategies, and patterning techniques. Readiness of these
processes for High-NA enablement is shown in more than 25 papers
presented at the 2024 SPIE Adv Litho & Patt Conference.”
On the material and process side, it is clear that metal-oxide resists
(MORs) are still in the lead for metal line/space patterns. Imec will
present the advancements of MOR in terms of EUV dose-to-yield
reduction. The selection of the specific underlayer, optimization of
the development process, choice of mask absorber, mask bias and
mask tonality were leading to a more than 20% dose reduction for
lines and spaces, without increased roughness or stochastic failures.
Also, tip-to-tip dimensions were not negatively impacted by these
dose reduction activities. The dose reduction work continues and
is highly appreciated by our chip makers, since it leads to EUV cost
reduction due to the higher scanner throughput.
An unexpected result was obtained by using MOR resists with a
binary bright field mask for contact hole patterning. A 6% dose reduction
with a 30% local CD uniformity (LCDU) improvement was
achieved after pattern transfer when comparing to a positive tone
chemically amplified resist (CAR) and a binary dark field mask transferred
in the same stack. A remaining concern of bright field masks
for contact holes is the mask quality and defectivity. This will need
careful investigation to make MOR an option for contact holes. Until
then, positive tone CAR resists with dark field masks will be the
leading candidates for contact and via patterning in High-NA EUV.
High-NA also requires improvements in metrology and inspection,
giving the higher resolution (by the high NA) and thinner films
(by the reduced depth of focus (DOF)). Imec will present new results
on e-beam and deep-UV (DUV) inspection, showing that new
best-known methods (BKMs) are in place to find High-NA relevant
stochastic patterning failures, such as hexagonal contact holes. In
addition, several machine learning techniques (based on denoising
SEM micrographs) will be proposed to facilitate the small defect inspection
and classification.
Finally, imaging improvements through source-mask optimizations
and anamorphic mask OPC (considering the need for stitching) will
be presented by imec and partners.
IMEC Belgium
3001 Leuven
Belgium
www.reinraum.de | www.cleanroom-online.com NEWSLETTER | Edition EN 04-2024
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