Fast and accurate X-ray lithography simulation enabled by using Monte Carlo method. New version of DoseSim: a software dedicated to deep X-ray lithography (LIGA)

This paper presents the recent development of a simulation tool for deep X-ray lithography. The simulation tool named DoseSim (Meyer et al. in Rev Sci Instrum 74(2):1113–1119, 2003) is a graphical user interface, working under Windows, specially dedicated to the necessary requirements of X-ray lithography setting at a synchrotron. The previous version included the computation of synchrotron radiation from bending magnets, the effects of the optical properties of materials, single mirror and the necessary parameters for the resist exposure. New functionalities, including among others, the exposure time calculation, the insertion of a double mirror, secondary effects (Fresnel diffraction, dose deposited under the absorber) have been added. Also, DoseSim includes traceability concerning the database and calculations used, and de facto the results obtained. Furthermore, Monte Carlo calculations using the PENetration and Energy LOss of Positrons and Electrons (PENELOPE) (Salvat et al.in OECD/NEA Data Bank, France, NEA N°6416, http://​www.​nea.​fr/​lists/​penelope.​html, 2008) code of the spatial distribution of the dose deposited by an X-ray beam in a resist are used. The PENELOPE results (simulations were done mono-energetically for a large range of energy) are the basis of the DoseSim routines for the calculations of the absorbed dose behind the absorber, and at the interface resist/seed layer/substrate. Example of calculations will be discussed along with the effects on dose from different seed layers and substrates.