The objective of this work is to describe the advances in 193nm photoresists using negative tone
developer and key challenges associated with 20nm and beyond technology nodes.
Unlike positive tone resists which use protected polymer as the etch block, negative tone
developer resists must adhere to a substrate with a deprotected polymer matrix; this poses
adhesion and bonding challenges for this new patterning technology. This problem can be
addressed when these photo resists are coated on anti-reflective coatings with plentiful silicon in
them (SiARC), which are specifically tailored for compatibility with the solvent developing
resist. We characterized these modified SiARC materials and found improvement in pattern
collapse thru-pitches down to 100nm.
Fundamental studies were carried out to understand the interactions between the resist materials
and the developers. Different types of developers were evaluated and the best candidate was
down selected for contact holes and line space applications. The negative tone developer
proximity behavior has been investigated through optical proximity correction (OPC)
verification. The defectivity through wafer has been driven down from over 1000 adders/wafer to
less than 100 adders/wafer by optimizing the develop process. Electric yield test has been
conducted and compared between positive tone and negative tone developer strategies. In
addition, we have done extensive experimental work to reduce negative tone developer volume
per wafer to bring cost of ownership (CoO) to a value that is equal or even lower than that of
positive tone CoO.