A semiconductor device and a method of fabricating the same includes providing a first semiconductor chip which has first connection terminals, providing a second semiconductor chip which comprises top and bottom surfaces facing each other and has second connection terminals and a film-type first underfill material formed on the bottom surface thereof, bonding the first semiconductor chip to a mounting substrate by using the first connection terminals, bonding the first semiconductor chip and the second semiconductor chip by using the first underfill material, and forming a second underfill material which fills a space between the mounting substrate and the first semiconductor chip and covers side surfaces of the first semiconductor chip and at least part of side surfaces of the second semiconductor chip.