Computation and experiments on the beam spread in the VP-SEM: Application to X-ray microanalysis

X-ray microanalysis (XRMA) coupled to a variable pressure scanning electron microscope (VP-SEM) using air atmosphere in the specimen chamber performed on test structures were used to make comparison with a Monte Carlo simulation program based on the modeling of the electron beam-gas interaction. The results show that the extent of the beam spreading can be significantly reduced at relatively high pressures by using helium gas instead of air and considerably reduced even at low pressure by lowering the analytical distance.