Three-dimensional　(3D)　integrated　circuit　(IC)　technology　is　considered　as　the　preferred　More-than-Moore　approach　due　to　its　capabilities　of　miniaturization,　high　density　and　multi-function.　And　through　silicon　via　(TSV)　is　the　key　enabling　technology　of　3D　integration.　So　now　TSV　is　getting　more　and　more　attention.　However,　TSV　manufacturing　processes　are　still　facing　several　challenges,　one　of　which　is　known　as　TSV　protrusion.　This　is　a　potential　threat　to　the　backend　interconnect　structure,　since　it　can　lead　to　cracking　or　delamination.　In　this　work,　we　studied　the　behavior　of　TSV　Cu　protrusion　under　different　thermal　cycling　numbers.　The　TSV　Cu　protrusion　was　measured　with　white　light　interferometry　(WLI)　of　subnanometer　scale.　The　results　help　to　solve　a　key　TSV-related　manufacturing　yield　and　reliability　challenge.