Cold-development is well-known for resolution enhancement on ZEP520A. Dipping a wafer in a developer
solvent chilled by a freezer, such a typical method had been employed. But, it is obvious that the
dip-development method has several inferiorities such as developer temperature instability, temperature
inconsistency between developer and a wafer, water-condensation on drying.
We then built a single wafer spin-develop tool, and established a process sequence, to solve those difficulties.
And, we tried to see their effect down to -10degC over various developers. In specific, we tried to make hole
patterns in hexagonal closest packing in 40nm, 35nm, 30nm, 25nm pitch, and examined holes pattern quality
and resolution limit by varying setting temperature from room temperature to -10degC in the
cold-development, as well as varying developer chemistry from the standard developer ZED N-50 (n-amyl
acetate, 100%) to MiBK and IPA mixture which was a rinsing solvent mixture originally. We also examined
the other developer (poor solvent mixture) we designed, N-50 and fluorocarbon (FC) mixture, MiBK and FC
mixture, and IPA+FC mixture.
This paper describes cold-development tool and technique, and its results down to minus (-) 10degC, for
ZEP520A resolution enhancement to obtain 1Xnm bits (holes) in 25nm pitch to fabricate an EB master mold
for Nano-Imprinting Lithography for 1Tbit/in2 bit patterned media (BPM) in HDD development and