27 February 2012 Particle protection capability of extreme ultraviolet lithography mask carriers based on the gap effect and filter effect
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Abstract
In extreme ultraviolet lithography, particle-free mask handling is a critical issue because the use of pellicles is impractical. We measured the long-term change in the number of particle adders on a mask blank during transfer processes using a reticle SMIF pod (RSP) and a dual pod, which consists of an outer pod and an inner pod that holds the mask. In the RSP, the number of particle adders during the transfer test of a load port in air to an electrostatic chuck chamber in vacuum decreased from 0.053/cycle to 0.032/cycle because of a clean-up during the pumping down and purging operations. However, the number of particle adders during vacuum transfer did not change with long-term use. Moreover, we found that particles were added by mask blank sliding on a robot hand during vacuum transfer. In contrast, for the dual pod, no accident was observed during the 2000-cycle transfer test, and the number of particle adders was 0.004/cycle. We confirmed that the filter effect and gap effect for protecting the mask from particles were effective. We concluded that the dual pod was a reliable mask carrier for vacuum transfer.
© 2012 Society of Photo-Optical Instrumentation Engineers (SPIE) 0091-3286/2012/$25.00 © 2012 SPIE
Mitsuaki Amemiya, Kazuya Ota, Takao Taguchi, and Osamu Suga "Particle protection capability of extreme ultraviolet lithography mask carriers based on the gap effect and filter effect," Journal of Micro/Nanolithography, MEMS, and MOEMS 11(1), 013002 (27 February 2012). https://doi.org/10.1117/1.JMM.11.1.013002
Published: 27 February 2012
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KEYWORDS
Particles

Photomasks

Extreme ultraviolet lithography

Solids

Inspection

Pellicles

Protactinium

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