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High efficient mask logistics as well as safe and high quality mask storage are essential requirements within an
advanced lithography area of a modern logic waferfab. Fast operational availability of the required masks at the
exposure tool with excellent mask condition requires a safe mask handling, safeguarding of high mask quality over the
whole mask usage time without any quality degradation and an intelligent mask logistics. One big challenge is the
prevention of haze on high advanced phase shift masks used in a high volume production line for some thousands of
248nm or 193nm exposures.
In 2008 Infineon Dresden qualified a customer specific developed semi-bare mask storage system from DMSDynamic
Micro Systems in combination with a high advanced mask handling and an interconnected complex logistic
system. This high-capacity mask storage system DMS M1900.22 for more than 3000 masks with fully automated mask
and box handling as well as full-blown XCDA purge has been developed and adapted to the Infineon Lithotoollandscape
using Nikon and SMIF reticle cases.
Advanced features for ESD safety and mask security, mask tracking via RFID and interactions with the exposure tools
were developed and implemented. The stocker is remote controlled by the iCADA-RSM system, ordering of the
requested mask directly from the affected exposure tool allows fast access.
This paper discusses the advantages and challenges for this approach as well as the practical experience gained during
the implementation of the new system which improves the fab performance with respect to mask quality, security and
throughput.
Especially the realization of an extremely low and stable humidity level in addition with a well controlled air flow at
each mask surface, preventing masks from haze degradation and particle contamination, turns out to be a notable
technical achievement. The longterm stability of haze critical masks has been improved significantly.
Relevant environmental parameters like temperature, humidity, AMC (Airborne Molecular Contamination) and
particles are controlled online within the system and monitored via the Cleanroom Monitoring System and iCADA
RSM.
The storage system is well conditioned, based on a fine adjusted heating and cooling concept whereby the desired
temperature and humidity values are kept very stable even under high frequent mask transactions.
The in-house developed RFID system and traceability of masks within the Infineon Dresden Lithotool landscape is a
new and complex logistics improvement, decoupling masks from boxes, saving costs and time and reducing particles.
The presented hardware and software solution shows how the potential of automation and improved production
efficiency can be increased by such adapted systems even in a mature 200mm waferfab.
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