In order to further understand the processing sensitivities of the EUV resist process, TEL and imec have continued their
collaborative efforts. For this work, TEL has delivered and installed the state of the art, CLEAN TRACK™ LITHIUS
Pro™ -EUV coater/developer to the newly expanded imec 300mm cleanroom in Leuven, Belgium. The exposures
detailed in this investigation were performed off-line to the ASML EUV Alpha Demo Tool (ADT) as well as on the inline
ADT cluster with CLEAN TRACK™ ACT™ 12 coater/developer. As EUV feature sizes are reduced, is it apparent
that there is a need for more precise processing control, as can be demonstrated in the LITHIUS Pro™ -EUV. In
previous work from this collaboration1, initial investigations from the ACT™ 12 work showed reasonable results;
however, certainly hardware and processing improvements are necessary for manufacturing quality processing
performance. This work continues the investigation into CDU and defectivity performance, as well as improvements to
the process with novel techniques such as advanced defect reduction (ADR), pattern collapse mitigation with FIRM™Extreme and resolution improvement with tetrabutylammoniumhydroxide (TBAH).
As Extreme ultraviolet (EUV) lithography technology shows promising results below 40nm feature sizes, TOKYO
ELECTRON LTD.(TEL) is committed to understanding the fundamentals needed to improve our technology, thereby
enabling customers to meet roadmap expectations. TEL continues collaboration with imec for evaluation of
Coater/Developer processing sensitivities using the ASML Alpha Demo Tool for EUV exposures. The results from the
collaboration help develop the necessary hardware for EUV Coater/Developer processing. In previous work, processing
sensitivities of the resist materials were investigated to determine the impact on critical dimension (CD) uniformity and
defectivity. In this work, new promising resist materials have been studied and more information pertaining to EUV
exposures was obtained. Specifically, post exposure bake (PEB) impact to CD is studied in addition to dissolution
characteristics and resist material hydrophobicity. Additionally, initial results show the current status of CDU and
defectivity with the ADT/CLEAN TRACK ACTTM 12 lithocluster. Analysis of a five wafer batch of CDU wafers shows
within wafer and wafer to wafer contribution from track processing. A pareto of a patterned wafer defectivity test gives
initial insight into the process defects with the current processing conditions. From analysis of these data, it's shown that
while improvements in processing are certainly possible, the initial results indicate a manufacturable process for EUV.
As lithographic technology is moving from single pattern immersion processing for 45nm node to double patterning for
the next generation and onward to EUV processing, TEL is committed to understanding the fundamentals and improving
our technology to enable customers to meet roadmap expectations. With regards to immersion and double patterning
technology, TEL has presented a wide variety of technologies to advance the processing capability of our customers.
With regards to EUV technology, we have previously presented work for simulation and modeling of an EUV resist
system1 in order to further our understanding of the differences between resist performance from previous platforms and
currently available EUV resists. As it's currently unknown which direction resist suppliers will take with regards to
platform in order to surpass the current limitations in resolution, roughness and sensitivity trade off's, we need to
consider the implications of such kinds of novel platforms to track processing capabilities. In this work, we evaluated
two of the more promising materials, to determine processing sensitivities necessary for the development of new
hardware and process applications. This paper details the initial study complete for understanding the track process
parameters such as dissolution characteristics and the impact of film hydrophobicity. Fundamental processing
knowledge from 193 and 248nm technology is applied to understand where processing deviates from known sensitivities
and will require more development efforts.
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