Chemical identification & characterization of sub-20nm residues and defects with Nano IR PiFM

P. O'Hara
Molecular Vista, Inc.,
United States

Keywords: PiFM, AFM-IR, Nano IR PiFM, chemical identification, particle characterization


The need to identify the chemical composition of small defects (<20 nm) is critically important in today’s semiconductor manufacturing process. The defects of concern range from 10nm to 500nm and ultrathin residues, which the current batch of molecular analytical tools cannot address adequately since the indications are that many of the defects and residues detected are organic in nature. In this poster, a relatively new nanoscale technique called infrared photo-induced force microscopy (IR PiFM), which combines atomic force microscopy (AFM) and infrared (IR) spectroscopy with ~ 5 nm spatial resolution, is introduced. By utilizing a state-of-the-art tunable broadband IR laser (tunable from ~550 to > 4000 cm-1 with ~ 3 cm-1 spectral width over the entire range), truly nanoscale PiF-IR spectra that agree with bulk FTIR spectra can be acquired; PiF-IR spectra can be used to search the existing IR database to unambiguously identify the different chemical species (both organic and inorganic molecules) of sub-20 nm defects and monolayer residues via their IR signatures. PiFM images at fixed wavenumbers associated with the different chemical species provide chemical mapping in real space with ~ 5 nm spatial resolution, clearly illuminating multi-component defects and existence of residues. The PiFM data can provide unambiguous and speedy feedback to process engineers engaged in EUV lithography.