A　three-dimensional　(3D)　thermo-elastic　stress　model　based　on　the　displacement　method　was　developed　to　study　the　thermal　stress　distribution　in　the　solidified　silicon　ingot　in　a　directional　solidification　process.　The　temperature　field　was　obtained　from　a　3D　global　simulation　of　heat　transfer　in　the　furnace.　A　new　coupled　model　was　developed　to　account　for　the　interaction　between　the　silicon　ingot　and　the　quartz　crucible.　The　thermal　stresses　and　deformations　of　the　ingot　and　the　crucible　were　solved　simultaneously　in　a　strictly　coupled　way.　The　thermal　stresses　in　the　square-shaped　ingot　and　crucible　were　analyzed.　The　influence　of　the　thermal　expansion　coefficient　of　crucible　on　the　thermal　stresses　in　the　ingot　and　crucible　was　also　investigated.　The　numerical　results　show　that　the　crucible　has　important　impact　on　the　thermal　stress　in　the　silicon　ingot.　It　is　necessary　to　account　for　the　deformation　of　crucible　in　the　computation　model　of　thermal　stress　in　the　silicon　ingot.　The　material　property　of　a　crucible　also　has　important　effect　on　the　thermal　stress　in　the　ingot.　A　crucible　with　large　thermal　expansion　coefficient　is　beneficial　to　reduce　the　thermal　stress　in　the　silicon　ingot.　©　2011　IEEE.