In the scanner, various forces act on the EUV pellicle. Identifying the underlying causes of pellicle destruction is challenging, and the criteria for evaluating the lifetime of the pellicle are ambiguous. Therefore, it is essential to analyze the complex forces that affect the pellicle and investigate how they impact its durability. Particle defects, in particular, can significantly reduce the lifetime of the pellicle, leading to mechanical damage such as deformation or destruction. To investigate these effects, we examined how particle defects impact the pellicle in the scanner environment, classifying them based on the type of defect. We modeled a scenario involving mask stage acceleration and compared the impact of defect conditions on pellicles, considering the increased scanner speed of a high-NA scanner. The results show that the stress around the defect increases rapidly due to the acceleration of the pellicle after being deflected by gravity. The embedded defect shows the highest stress, which has the potential to decrease the lifetime of the pellicle due to repeated acceleration.
The extreme ultraviolet (EUV) pellicle on the EUV mask is used to prevent the image distortion, and the lifetime of the pellicle is important because it is directly related to the yield. However, particle defects can significantly impact the lifetime of the pellicle, causing thermal or mechanical damage such as deformation or increased temperature. To study these effects, we explored how particle defects affect the pellicle, including scenarios where defects on the pellicle or collide with it. We found that there was no temperature and stress accumulation with repeated exposure of the pellicle regardless of the defect exitance. The collision of flying particles gave little mechanical effect with the known impulse inside the scanner. The metal-silicide core pellicles showed better thermal stability compared to the poly-silicon core pellicles and that could be the reason why metal-silicide pellicles showed longer lifetime.
The pellicle prevents image errors due to contaminated particles in the EUV mask and protects the mask for a stable process. However, the lifetime of the pellicle could be shortened due to deformation and destruction caused by the collision of the particle defects in the chamber. Therefore, in order to increase the lifetime of the pellicle, it is required to develop an optimal pellicle material and structure that is resistant to deformation and destruction and has excellent mechanical stability. Accordingly, it is necessary to know the deformation caused by the particle collision and estimate the lifetime of the pellicles with different mechanical stability. In this study, we simulate the collision of particle defects for the pellicle and compare the mechanical stability depending on the single-layer pellicle materials.
For finer linewidth patterning, 0.55 numerical aperture (NA) should be used instead of the existing 0.33 NA. In 0.55 NA extreme ultraviolet lithography (EUVL), to alleviate the mask 3D effect and stochastic noise, which is stronger, it is necessary to develop an optimal phase shift mask (PSM) and multilayer mask for high NA. Mask structure is used PSM with composed of Ru-alloy/TaBO and multilayer composed of ruthenium (Ru)/silicon (Si), which is expected to be effective in mitigating mask 3D effect and improving imaging performance. The absorber reflectance was checked which is changed by variables such as pattern existence, target CD, and pitch ratio. In addition, by examining the relationship between the change in absorber reflectance and normalized image log slope (NILS), it was determined whether the mask structure for high NA was changed by the target pattern changes.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.