Using　2D　mixed-mode　device　simulation,　this　paper　examines　the　overcurrent　turn-off　or　reverse　recovery　of　a　3.3-kV　silicon　fast　recovery　diode.　Simulation　results　show　that　cathode-side　current　filaments　(CCFs)　play　more　roles　than　expected　during　the　overcurrent　reverse　recovery　under　severe　conditions.　The　actions　of　the　CCFs　include　cutting　and　squeezing　the　residual　plasma　within　the　ní　region,　and　promoting　the　formation　of　anode-to-cathode　solitary　current　filaments.　Both　the　width　of　the　lateral　resistance　zone　at　the　edge　of　the　main　junction　and　the　backside　n+　doping　can　affect　the　evolving　patterns　of　the　residual　plasma,　CCFs　and　anode-to-cathode　filaments,　which　in　turn　determines　the　intensity　of　the　final　solitary　filament,　and　thus　the　chance　of　survival　of　the　device.　©　2019　IEEE.