Abstract: Effects of SEU and SEB are simulated with 0.4μm diameter microbeam. SEU for drain region of MOSFET and CMOS SRAM are calculated. Collective charge depending on LET for specific device structure is calculated for different ions. LET and critical charge are provided. SEB for VDMOS is simulated and electric field, potential line, current, rate of impact ionization are given at different times along ion tracks. It is very important for heavy microbeam test physics models which have been set up.