Monte Carlo study of backscattered electron signals from microstructures of x-ray masks

A Monte Carlo simulation has been performed to analyze backscattered electron signals from typical x-ray mask samples such as microstructures of steps and holed. The discrete energy loss process and the fast secondary electron production are included in the simulation. The microstructures analyzed here are an Au step and a hole in an An film on Si substrates. The heights and the widths of the step and the hole are both 0.5 mum. Incident and exit energy dependences of the backscattered electron signals have been studied with the simulation. From these studies it is found that the peak position of the signals, which characterizes the shape of the microstructures, depends on the incident electron energy and these peaks mainly consists of low-loss backscattered electrons. It is also shown that the shape and the intensity of the signals depend on the detection angle of the backscattered electrons.