October 4, 2006 – Researchers at SEMATECH North in Albany, NY, claim to have successfully patterned features narrower than 45nm (half-pitch) in multiple orientations using 193nm immersion lithography and azimuthal polarization, which allows for aggressive imaging of arbitrary circuit features beyond simple line-and-space test patterns. Work was presented at the 3rd annual International Symposium on Immersion Lithography in Kyoto, Japan.
The researchers used an Exitech immersion projection microstepper (NA=1.3) with optical proximity correction and other resolution enhancement techniques to simultaneously image sub-45nm linewidths along X and Y axes within the same field, with resulting pitch of 84nm.
Resist stack optimization of dual-layer bottom anti-reflective coating systems were also utilized in combination with OPC and RET strategies, and researchers selectively rotated linear-polarized light at the coherence aperture to simultaneously image the sub-45nm features, according to Andrew Grenville, associate director of SEMATECH’s lithography division.
The achievement marks the only OPC model to be validated against experimental results, according to SEMATECH, and provides “patterning capability beyond anything able to obtained on projection exposure tools today,” noted Grenville, in a statement. “With this toolset, we are demonstrating feasibility that 193nm [immersion] can be used for 45nm half-pitch manufacturing.”