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EUV lithography is expected to be the key lithography option for sub-22nm device manufacturing. In order to meet the
required imaging capability, resist performance improvements are being investigated by exploring both chemically
amplified resists (CAR) and non-CAR chemistries. Another critical item related to resist chemistry is the EUV
irradiation induced outgassing and its risk for optics contamination, especially towards high source power (pre-)
productions tools. In this area it is important to characterize for the different chemistries which resist components are
critical for EUV induced outgassing and - more important - which can result in non-cleanable mirror contamination.
In this paper, we will explore the outgassing and contamination behavior of CAR and non-CAR resist by using Residual
Gas Analysis (RGA) for identifying the resist outgassing characteristics, and by Witness Sample (WS) testing to evaluate
the tendency for contamination. For CAR resists, it has been found that the PAG cation is a key component contributing
to the contamination, but its impact can be changed by changing the resist formulation. In this investigation several
model resists have been evaluated in order to understand which chemical components have - or don't have - an impact
on the contamination. This has led to a proposal of a definition for a resist family. For non-CAR materials, the
investigation has focused to a number of example resists. Most results are related to poly(-olefin sulfones), which have
been proven to be good candidate materials for outgassing and contamination learning. The tests have confirmed that
aromatic groups present in resist outgassing are playing an important role. As an opposite example of non-CAR
material, the inorganic Inpria resist was tested, which revealed that its resist outgassing (water and oxygen) can remove
carbon contamination.
The combined work on CAR and non-CAR outgassing and contamination has learned significantly on the relationship
between resist chemistry, its outgassing and contamination, and provided understanding on how to design good
performing EUV resists with minimal risk for optics contamination in EUV device manufacturing.
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