Doctoral research project

Person in charge of the project:
VAN DEN HOVE LUC, member of research team Associated Section of ESAT - INSYS, Integrated Systems
Title:
Modelling and Experimental Evaluation of (Post)Lithography Process Contributions to Pattern Roughness
Project summary:
Process variability in today’s lithography might be a showstopper for extreme-UV lithography for the 32 nm technology node and beyond. At these feature sizes, electrical devices are influenced by quantum effects and thus have to face the discrete behaviour of light and matter. Lithography uncertainties such as photon shot noise, photomask roughness, diffusion and thermal processes of the photoresist material, fractal behaviour of chemical species and polymer deprotection noise, have been assessed through extreme UV lithography exposures and simulated predictions. Stochastic contributions of each lithographic element to the feature’s variability such as source, photomask, optical system, photoresist material response and metrology setup were evaluated. The resulting roughness of the printed features was then measured and injected into Monte Carlo simulator for electrical evaluation on multi-level NAND Flash memory cells array. Electrical simulations allowed us to create a link between material-level variability (photoresist feature roughness) and system-level reliability (bit error rate), showing how significant the lithography contribution is on the electrical performance of devices for features sizes below 20 nm.
ph.D student :
VAGLIO PRET ALESSANDRO
Faculty of Engineering Science
Doctoral Programme in Engineering (Leuven)

ph.D defence : 07.09.2012
Full text ph.D