High-performance imprint lithography and novel metrology methods using multifunctional perfluoropolyethers

摘要

We describe the use of multifunctional perfluoropolyethers as enabling materials in imprint lithography and metrology. Perfluoropolyethers (PFPEs) are a unique class of fluoropolymers that are liquids at room temperature that can be functionalized and cured to form transparent "PTFE-like" elastomers. These materials posses many favorable attributes relative to imprint lithography and other soft lithographic techniques including: chemical resistance, flexibility, incredibly low surface energies, high gas permeability, and UV transparency. Molds made from PFPE materials exhibit the favorable properties of both rigid and soft materials in that they are rapidly made and disposable, yet maintain the chemical resistance and performance of rigid materials such as quartz. We have previously demonstrated the use of such materials in patterning 70nm features with a precision of +/-1 nm. Herein, we further demonstrate the capability of these materials in the rapid patterning of dual damascene structures and other patterns. The chemical resistance of PFPE-based materials allows for the patterning of a variety of organic resins including etch resists, low-k dielectrics, and conducting polymers. Additionally, we demonstrate the utility of functional PFPEs in a novel metrology method. In this simple technique, the liquid PFPE precursor is poured onto a wafer with a given pattern and cured. When released from the wafer, the cured film possesses an exact negative replica of the original pattern. A variety of metrology and inspection methods can then be performed on the patterned, transparent film including microscopy and through-film optics which can reveal defects in the original pattern. Furthermore, the method is shown to be completely non-destructive to the original patterned wafer. We describe the use of this method in the metrology and inspection of a dual damascene pattern containing features which are difficult to characterize by other techniques.