Advanced mask metrology enabling characterization of imprint lithography templates

Lithography costs for IC production at resolutions of 65-nm and beyond have grown exponentially for each technology node and show no sign of slowing. Step and Flash Imprint Lithography (S-FIL (TM)), developed at the University of Texas (UT) uniquely offers IC manufacturers the potential for lower cost of ownership, because S-FIL does not require expensive optics, advanced illumination sources or chemically amplified resists (CAR). The SIA's addition of Imprint Lithography to the International Technology Roadmap for Semiconductors (ITRS) in 2003, indicates the promise to become a preferred technology and has some compelling advantages over traditional 4X optical lithography. Advanced 90nm binary & phase shift mask processes have been altered using thin Cr (15-nm) & thin e-beam resist (< 150nm) resulting in sub 100-nm geometries necessary for S-FIL, and have become the baseline for template manufacture. Commercial production of advanced 1X templates requires CD metrology capability beyond the equipment typically used in 4X mask making. Full commercialization of Imprint Lithography requires not only the ability to generate a 1X template but also a metrology solution that can characterize critical dimension (CD) parameters of the template. Previous published work on S-FIL has focused mainly on high resolution templates produced on 100keV Gaussian pattern generators (PG), and has shown that resolution is only limited by the template(1,2,3). This work demonstrates that an advanced commercial photomask facility can fabricate templates with sub-100 nm critical dimensions, and that the CDs can be characterized using a commercially available CD-SEM metrology tool. CD metrology repeatability of 0.7nm 3 sigma was established on a quartz only template with a 6025 form factor.