AVS 61st International Symposium & Exhibition
    Applied Surface Science Monday Sessions
       Session AS+BI+MC+SS-MoA

Paper AS+BI+MC+SS-MoA9
Low Temperature Plasma for Crater Edge Depth Profiling of Crosslinking Organic Multilayers: Comparison with C60 and Argon Cluster Sputter Sources

Monday, November 10, 2014, 4:40 pm, Room 316

Session: The Liquid Interface & Depth Profiling and Sputtering with Cluster Ion Beams
Presenter: Shin Muramoto, National Institute of Standards and Technology (NIST)
Authors: S. Muramoto, National Institute of Standards and Technology (NIST)
D. Rading, ION-TOF GmbH, Germany
B. Bush, National Institute of Standards and Technology (NIST)
G. Gillen, National Institute of Standards and Technology (NIST)
D.G. Castner, University of Washington
Correspondent: Click to Email
A model organic layer system consisting of three 1 nm delta layers of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) separated by three 30 nm layers of tris(8-hydroxyquinolinato)aluminum (Alq3) was used to evaluate the effectiveness of helium low temperature plasma (LTP) etching for the preparation of crater edge surfaces for subsequent compositional depth profile analysis. The quality of the depth profile was determined by comparing the depth resolutions of the BCP delta layers obtained from the plasma-etched craters with those obtained using ToF-SIMS dual-beam depth profiling equipped with C602+ and argon cluster (Ar1000 to 2500) sputter sources. Using the full width at half maximum (FWHM) of each delta peak, the depth resolutions of the second and third delta layers were measured to be 6.9 nm and 6.0 nm for the plasma-etched crater, respectively, which were very close to the depth resolutions of 6.2 nm and 5.8 nm obtained from the argon cluster depth profile. In comparison, the use of a 1/e decay length to approximate the depth resolution gave results that identified the artifacts caused by ion bombardment in SIMS depth profiling. The 1/e decay length for the trailing edge of each delta were 2.0 nm and 1.8 nm for the plasma-etched crater, respectively, while the argon cluster depth profile gave decay lengths of 3.5 nm and 3.4 nm, owing to the longer tails produced by artifacts and possibly by slower sputter rate through the delta layers. For the C602+ depth profile, the need to rescale the axis as a result of a strong nonlinear sputter rate gave artificially improved depth resolutions, where FWHM of the delta peaks were 5.6 nm and 7.3 nm, respectively, and 1/e decay lengths were 1.7 nm and 2.3 nm, respectively. Although some artifacts such as contaminant deposition remain, low temperature plasma was shown to be a viable option for creating crater edges for compositional depth profiling without artifacts seen in ToF-SIMS depth profiling.