First experimental evaluation of accelerated reticle lifetime testing using an applied bias voltage at EBL2
conference paper
Reticles interact with EUV photons and EUV-induced hydrogen plasma in EUV lithography equipment. These interactions can lead to hydrogen uptake and hydrogen induced outgassing. Hydrogen diffusion into the coating layers can contribute to blistering (bubble formation) and even delamination of layers. Our experimental study focusses on optimizing conditions during accelerated lifetime testing in our EUV beamline (EBL2). We will show that applying a bias voltage to the test sample during exposure accelerated blister formation by at least a factor 3. We exposed Ta-based reticle blank samples to EUV photons and EUV-induced hydrogen plasma in the TNO EBL2 facility. Two very similar tests were performed, one with and one without an applied bias voltage. No blisters were observed for the exposure of the grounded sample. Blister formation and partial delamination was clearly observed when a voltage of -30V was applied during EUV exposure. We will show results of in-situ ellipsometry obtained during exposure. This data shows the exact time and location of blister formation and shows the dynamics of further blister growth and delamination. Comparing both exposures, we find that the blistering rate is at least 3 times higher in the presence of -30V sample bias. Additionally, in-situ XPS, optical microscopy, SEM and TOF-SIMS was used to further clarify the blistering mechanism. Results show that the blister delamination occurs at the cap/multilayer interface. The uptake of hydrogen in the coating and the relationship of the blister locations with the EUV intensity distribution are discussed. This research helps to understand the impact of bias voltage on reticle degradation. Results suggest that applying bias voltage is a very promising method to accelerate blistering in our test setup, which paves the way for more cost-efficient testing and validation of reticle coatings. © 2025 SPIE. All rights reserved
Topics
TNO Identifier
1023317
ISSN
0277786X
Publisher
SPIE
Article nr.
136870B
Source title
Photomask Technology 2025, Monterey, 2025-09-22 through 2025-09-25
Editor(s)
Melvin, L.S.
Philipsen, V.
Philipsen, V.
Pages
1-10
Files
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