A stackable semiconductor device and a manufacturing method thereof are disclosed. The method includes providing a wafer comprised of a plurality of chips, wherein a plurality of solder pads are formed on the active surface of each chip, and a plurality of grooves are formed between the solder pads of any two adjacent ones of the chips; forming a dielectric layer on regions between the solder pads of any two adjacent ones of the chips ; forming a metal layer on the dielectric layer electrically connected to the solder pads and forming a connective layer on the metal layer, wherein the width of the connective layer is smaller than that of the metal layer; cutting along the grooves to break off the electrical connection between adjacent chips; thinning the non-active surface of the wafer to the extent that the metal layer is exposed from the wafer; and separating the chips to form a plurality of stackable semiconductor devices. Accordingly, a multi-chip stack structure can be obtained by stacking and electrically connecting a plurality of semiconductor devices through the electrical connection between the connective layer of a semiconductor device and the metal layer of another semiconductor device, thereby effectively integrating more chips without having to increase the stacking area, and further the problems of poor electrical connection, complicated manufacturing processes and high costs known in the prior art can be avoided.