Optimized molecule supply from nozzle-based gas injection systems for focused electron- and ion-beam induced deposition and etching: simulation and experiment

V Friedli, I Utke
2009 Journal of Physics D: Applied Physics  
We simulated and measured near-field distributions of molecules impinging on a flat substrate from tube-based nozzles with varying exit aperture geometries (straight, bevelled and doubly perforated). Simulations were performed with the test-particle Monte Carlo approach taking into account the Knudsen number (molecular/transient flow) at the nozzle exit. Distributions were measured via thermal decomposition of Co 2 (CO) 8 molecules on a homogeneously heated substrate. For all geometries and
more » ... sen numbers a good match between the simulation and experiment was found. For the first time the maximum accessible molecule flux with respect to the total flux exiting the nozzle could be quantified: it is around 7% for a straight cylindrical tube, around 27% for a bevelled tube and around 32% for a doubly perforated tube, all nozzles being 300 µm distant from the substrate and having a 400 µm aperture. Optimum substrate-nozzle angles were determined and shadow effects quantified.
doi:10.1088/0022-3727/42/12/125305 fatcat:4e5jj2ze25holiugpk6c7adzbe