Nanoscale Pattern Decay Monitored via in-situ Heated Atomic Force Microscopy
Sonal Bhadauriya, Jianan Zhang, Jaejun Lee, Michael R. Bockstaller, Alamgir Karim, Richard J. Sheridan, Christopher M. Stafford
We combine in-situ heated atomic force microscopy (AFM) with automated line-by-line spectral analysis to quantify the relaxation or decay of nanopatterned polymer films at temperatures above the glass transition. This approach enables assessment of pattern fidelity with a temporal resolution of 1 s, providing the necessary data density to confidently capture the short time relaxation data as compared to conventional off-line serial measurements. Specifically, we studied the thermal decay of nanopatterned PMMA and PMMA composite films (containing unmodified and PMMA-grafted silica nanoparticles, SiO2 NP) of varying concentrations and film thicknesses using this new approach. Nanofeatures fabricated on neat PMMA films were seen to relax at least an order of magnitude faster than the filled films at decay temperatures above the glass transition of the PMMA matrix. It was also seen that patterned films with the lowest residual thickness filled with unmodified SiO2 NP decayed the slowest. The effect of additive system was almost negligible in reinforcing the patterned features for films with the highest residual thickness. Our in-situ pattern decay measurement and the subsequent line-by-line spectral analysis enabled the investigation of various parameters affecting the pattern decay such as the underlying residual thickness, type of additive system, and the exposure temperature in a timely and efficient manner.