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Immersion materials have to overcome immersion-issues for successful wet process introduction to semiconductor
mass production. Component-leaching issue is one of the most influential wet process huddles, which is related to
immersion-liquid and projection lens contamination as well as resist patterning performances. In this paper, we will
introduce our experimental results of leaching blocking effects resulted from the modification of polymer and additive
structures and from the application of top surface blocking layers. PAG-leaching level of resist film formed of low Tg
resin shows the highest meanwhile that of high Tg resin is the smallest leaching value. The interaction forces between
additives and resin platforms are the most important to prevent additives leaching to immersion liquid.
We have tested 3 different types of resin structures to modify the interaction forces between resin platform and resist
components especially PAG molecules and photo-generated acid molecules. We changed 2-hydroxyethyl
methacrylate(2-HEMA) contents to be 5, 10, 15% in our base resin, COMA-acrylate hybrid system to modify the
hydrophilicity of resist platforms. By mimicking immersion process to obtain wet-performance of their resists we have
obtained relative value of component-leaching. Interaction-force between resist platform and PAG was seemed to be
largest when resist component-leaching is least so that the pattern profiles become to be vertical. It was appeared that
the 5% 2-HEMA containing resin and TPS-Nonaflate PAG system showed the best performance because of its low
leaching resulted from their strong interaction forces.
Another polymer parameter to determine the component-diffusivity is glass transition temperature, Tg. Low Tg
means high mobility of resin by small thermal energy due to high free volume contents inside of the resist film which
can act as diffusion pathways of resist components. 10% MA resin system shows the lowest Tg, around 140 degrees C and the
most serious T-topping profiles.
Defectivity issue becomes more important in immersion process, which is most related to the partial leaching by
residual water and resulted in watermark defects. We evaluated the relative easiness of watermark formation on
different resist films by correlations between static and dynamic contact angles. We made 2 different resist films
composed of 2 different water-repellent functional group monomers. Static contact angles of developer as well as DI
water were measured. It was found indirectly that amphiphilicity of resist film surface makes positive effect on
watermarks formation, that is, more hydrophobic and more developer-philic resist film remains less residual water
droplets.
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