by M. David Levenson, Editor-in-Chief, Microlithography World
Feb. 25, 2008 – Claiming the ability to print 32nm, 28nm and 22nm features at 4WPH with 35nm overlay, Molecular Imprints, Inc. (MII) says its latest imprint lithography tool for semiconductor applications, the Imprio 300, introduced at the SPIE Advanced Lithography Symposium on Feb. 25., is the “only game in town” for semiconductor prototyping and process development in the <30nm realm.
“Our unique technology imprints into liquid at room temperature, facilitating overlay,” according to CEO Mark Melliar-Smith, who discussed the technology in an interview with WaferNEWS. The step and flash tools are drop-in replacements for optical exposure tools, completely compatible wit current processes.” He provided slides showing that working FinFET transistors have already been patterned at 20 and 30nm and resist CD uniformity demonstrated at 0.8nm with LER<2nm.
Molecular Imprint’s stepping tools dispense the resist as droplets with density scaled to the local duty factor inside each imprint field. That results in a highly-uniform residual resist layer after imprint, which, they claim, can be removed using standard descum processes.
The Imprio 300 is targeted for memory applications where circuit density is paramount. For NAND flash architectures, density and cost-of-ownership trump overlay, perhaps opening a niche for imprint lithography, according to Melliar-Smith. Over small fields, however, the Imprio 300 claims an overlay precision (mean +3[σ]) below 10nm. He estimated that the throughput of the Imprio 300 would make its CoO compatible with that of 193nm immersion and less than EUVL prototypes. Experience with previous-generation tools also led Molecular Imprints to improve the graphical user interface and operator features of the Imprio 300. First shipment of the new system is scheduled for mid-2008.
Melliar-Smith also discussed Molecular Imprints’ roadmap to make the company the world leader in sub-30nm lithography for flash memory. A high-volume manufacturing tool with 15nm overlay and 20 WPH throughput is on track for introduction in 2010. At the 22nm flash node, that tool would be less expensive to operate than EUVL or spacer-type double patterning, in part because of its use of replicated templates. He also predicted that the disc drive industry will be ramping up patterned media production in 2010. In that technology, one disc will hold 1013 30nm posts (on each side), each post corresponding to a bit of data. Molecular Imprints is developing high-throughput tools based on their Imprio 1100 technology for that full-field application.
Melliar Smith counted eight papers by MII customers at the 2008 Advanced Litho Symposium, plus four papers presented by MII itself, as evidence of the increasing acceptance of step and flash imprint. — M.D.L.