One　of　the　main　failure　modes　of　an　insulated-gate　bipolar　transistor　(IGBT)　module　is　the　reconstruction　of　an　aluminum　(Al)　metallization　layer　on　the　surface　of　the　IGBT　chip.　In　this　study,　experimental　observations　and　numerical　simulations　were　used　to　investigate　the　evolution　of　the　surface　morphology　of　this　Al　metallization　layer　during　power　cycling,　and　both　internal　and　external　factors　affecting　the　surface　roughness　of　the　layer　were　analyzed.　The　results　indicate　that　the　microstructure　of　the　Al　metallization　layer　evolves　during　power　cycling,　where　the　initially　flat　surface　gradually　becomes　uneven,　such　that　the　roughness　varies　significantly　across　the　IGBT　chip　surface.　The　surface　roughness　depends　on　several　factors,　including　the　grain　size,　grain　orientation,　temperature,　and　stress.　With　regard　to　the　internal　factors,　reducing　the　grain　size　or　orientation　differences　between　neighboring　grains　can　effectively　decrease　the　surface　roughness.　With　regard　to　the　external　factors,　the　reasonable　design　of　the　process　parameters,　a　reduction　in　the　stress　concentration　and　temperature　hotspots,　and　preventing　large　local　deformation　can　also　reduce　the　surface　roughness.