This　study　investigates　the　mechanism　of　electron　redistribution　and　multiplication　for　a　SiO2　sample　with　a　buried　structure　in　scanning　electron　microscopy　by　numerical　simulation.　The　simulation　involved　electron　scattering　and　internal　charge　transport　in　the　sample,　the　tracking　of　emitted　secondary　electrons　(SEs),　and　the　generation　of　tertiary　electrons　(TEs)　produced　by　returned　SEs　due　to　charging　of　the　sample.　The　results　show　that　a　buried　grounded　structure　causes　a　non-uniform　distribution　of　surface　potential,　and　an　electric　field　above　the　surface.　As　a　result,　although　the　number　of　escaped　SEs　above　the　margin　of　the　buried　structure　decreases,　the　number　of　generated　TEs　increases　more,　leading　to　a　final　current　of　electrons　that　include　escaped　SEs　and　increased　TEs.　This　multiplication　of　SEs　might　make　a　crucial　contribution　to　the　abnormal　negative-charging　contrast　in　SEM.　During　the　electron　beam　irradiation,　the　variation　in　the　number　of　total　escaped　electrons　presents　an　obvious　increase　after　an　initial　slight　decrease,　which　corresponded　to　the　transient　characteristics　of　gray　levels　in　SEM　images　from　dark　to　abnormally　bright.　(C)　2016　Elsevier　Ltd.　All　rights　reserved.