In　order　to　study　the　failure　of　IC　devices　induced　by　the　stress　in　VLSI　metal　interconnect,　In-situ　observation　of　the　stress　changes　of　VLSI　Al　interconnect　was　studied　under　the　electromigration　and　thermal　conditions　by　using　a　synchrotron　radiation　x-ray　diffraction　technique.　The　tensile　stress　in　deposited　Al　interconnects　was　measured　in　the　room　temperature.　During　the　annealing　process,　the　tensile　stress　gradually　decreased　and　then　conversed　into　the　compress　stress　at　the　temperatures　between　300°C　and　350°C.　During　the　electronmigration　tests　in　the　range　of　3　×　105　A/cm2　and　4　×　106　A/cm2　for　275　min,　the　tensile　stress　at　the　anode　of　Al　interconnects　changed　into　the　compress　stress,　which　then　increased　with　the　increasing　of　current　density.　Furthermore,　the　electronmigration　failure　characteristic　and　the　stress　relax　of　Al　interconnects　was　observed　by　using　the　SEM.