We have studied on theoretical electron energy deposition in thin resist layer on Si substrate for electron beam lithography. We made Monte Carlo simulation to calculate the energy distribution and to consider formation of nanometer sized pattern regarding electron energy, resist thickness and resist type. The energy distribution in 100 nm-thick resist on Si substrate were calculated for small pattern. The calculations show that 4 nm-wide pattern will be formed when resist thickness is less than 30 nm. Furthermore, a negative resist is more suitable than positive resist by the estimation of a shape of the energy distribution.