In a semiconductor device fabricating method, a plurality of wafers each having a plurality of chips into is carried and is placed in a die bonder. Chips taken out from the plurality of wafers is bonded together, respectively, and superpose in a stack by bonding layers to form a chip assembly. The chip assembly to a die pad by a bonding layer is bonded. Thus, the die bonder is able to bond the chip assembly consisting of the plurality of chips to the die pad, so that the process time of a die bonding process for bonding the plurality of chips to the die pad is comparatively short, the semiconductor fabricating apparatus produces semiconductor devices at an improved productivity, has a comparatively small scale and needs a comparatively low equipment investment.