Proceedings Article | 24 March 2008
Proc. SPIE. 6922, Metrology, Inspection, and Process Control for Microlithography XXII
KEYWORDS: Lithography, Multilayers, Metrology, Polymers, Silicon, Monte Carlo methods, Photomasks, Extreme ultraviolet lithography, Critical dimension metrology, Stochastic processes
Strong candidate lithography for the mass production of devices at the 32nm technology node and beyond is extreme
ultra violet lithography (EUVL). The mask used in EUVL is a complex set of layers. The material composition and
thickness of each layer should be considered explicitly in an attempt to model the deposited energy in the resist film
during fabrication of mask features using electron-beam lithography. Targeting to sub-32nm technology even with the
reduction by 4 of the mask features on the wafer level, lithography should consider accurate fabrication features on the
mask level of the order of 50nm. Therefore, detailed simulation of the electron-beam fabrication process, as well as the
resist dissolution mechanism and etching is demanding. In this work an attempt is initiated targeting in combining two
simulation techniques i.e., the electron-beam simulation, with the stochastic lithography simulation, in a common
simulation platform. This way it will be possible to get detailed information of the fine details of the fabricated features,
taking into account the multilayer substrate of the mask, and the resist material properties. The e-beam simulation
algorithm is presented and used to expose a layout. The calculated energy deposition in the resist level, initially
determined considering resist material to be continuous, is used in the discrete representation of the resist. With
appropriate threshold in the exposure energy, also acid diffusion could be taken into consideration. Stochastic
development of the resist material, delivers line-edge roughness (LER) and critical dimension (CD) on the resist level, in
terms of polymer chain architecture.
